I'm pretty certain the only HT-HG with standard dual exhaust was an 81837. It took until the HX GTS before a Holden V8 was standard with dual exhaust, although the HQ SS got a dual system (and 3.36 rear axle which made a standard HQ GTS 308 very surprised).
Correct, HT-HQ 308 auto rear axle ratio was all 3.36 standard fitment.

I agree a dual exhaust manual 307 or 308 HT or HG would be close to an XT GT, but the single exhaust versions no. Wouldn't take much to quicken up an XT GT though as it had 10:1 compression and was a nice motor. 3.25 gears and a Quadrajet or 600cfm Holley and it'd be far quicker.

HT-HG GTS350 auto were not a slow car, they were still a tad over 9:1 engine and the only difference between this engine and the manual car was the head chamber sizes and 2 bolt block rather than 4 bolt. Valves, intake, carb (other than vacuum source for dizzy), dizzy, cam, pistons, crank etc all the same. They did have a 3.08 rear axle as standard but 3.36 was optional. In fact the Press were very impressed, even more so when they timed these (with air and/or steer) to be not far off the manual cars, without knowing that GMH had hidden the manual car's true performance. A standard HT GTS350 auto optioned with A/C and power steering as tested by the press at the time managed 16.0s 1/4 mile @90mph, 117mph top speed and 0-100mph is 22.0s. This was letting the auto do its thing, not manual shifting. Apart from the top speed limitation of the auto transmission that is pretty much line ball with an XT GT as tested by the same methods by the same people and faster than the automatic GT. The XW GT auto would have easily had its measure though, but may have got a bit of a shock coming up against one optioned with a 3.36 rear end and no air or steer as that would be a significantly closer match.

Edited by user Friday, 12 October 2018 3:17:09 PM(UTC)  | Reason: Fixed rear axle ratio for 308 auto HT-HG

And the reclining versus fixed bucket seat thing Warren, very odd. Luckily tyres were free or they'd be after 200 cars with the same diff ratio, same seats backs AND same tyres! Imagine if all Salisbury units weren't LSD? Or if the HK Kingswood raced had an LSD or an alternate rear axle ratio as well as 186S, 4spd and reclining bucket seats? GMH found over 200 of these cars with standard rear axle, but my guess is the same thing with LSD or 3.08 rear axle would be lucky to be a handful of cars made.

Edited by user Friday, 12 October 2018 3:03:41 PM(UTC)  | Reason: Not specified

My question was more to why they did it, not the choice of gearbox. Was it do to with the homologation being spoken about here?

I have been circling back to this (refer post 3 in this thread). I have obtained a whole lot more info and also been talking to Ron Marks who categorically states that he crossed the line first in 1968. I have a whole lot of questions for Ron to fill in for me, so will report back. Just waiting on a few other key bits of info.

He knows he won, he was in the car for the last stint.

Few more notes on this I'll share.

Ron Marks was in the car for the 3rd stint, he drove it home. As far as he was concerned, Des was leading when he bought the car in for its second stop which was for one tyre and fuel. 14D never changed brake pads hence why it was leading, that is why it was always effectively in front, everyone else changed pads. This was Bruce Burr's strategy. Ron got in and drove it home with very little brakes. No-one overtook him except for the 9D Seton/Gibson car around 1:43pm (see more below).

Note on brakes. The best evidence of what a brake pad pit stop looked like is recorded by Peter Wherrett. At 10:40 am, the Palmer/West HDRT 24D car made its first stop. It was fuel, front pads and driver change. Des West pitted at 11:17 for fuel, and the car took 22.5 Gallons of fuel, so 24D at 10:40 would have been maybe 16Gallons, so the pit stop time of just under 6 minutes was the pad change time, it would easily have covered fuel.

Some milestones to think about:

12:20pm. Race order was 9D (Gibson), 14D (West), 8D (Geohegan), 13D (McPhee). The two Falcons were up in the mix as they had all done 1 stop only so far (except 23D had done two) and the 23D and 24D HDRT cars had already done pads in their first stops.
12:27pm 8D Geohegan car in for fuel, tyres and driver change.
12:45pm 9D in for pads, fuel, tyres and driver change.
12:51pm 24D in again for driver change, pads (again) and tyres. No more stops for 24D
1.00pm 25D in for driver change and fuel.

80 laps (approx 1.15pm) order was 14D, 9D, 13D, 23D, 25D, 24D, 15D 1E. 8D was out of the race at this time, spent 30 minutes in the pits with failed brakes.

1.41pm 13D in for fuel, tyres, front brake pads and for Bruce to hand over to Barry Mulholland. This would have been a 5 minute stop at least.
1.42pm 23D in for tyres and fuel. Pads changed again.
1.43pm 14D in for 21 gallons of fuel and for Des to hand over to Ron Marks. 9D took the lead at this stage, possibly also overtaken by 13D (unsure of this at this stage but really irrelevent).
1.44pm 13D in for Barry to hand back over to Bruce.
2.06pm 25D in for brake issues, 9 minutes spent in the pits, that is 3 laps. It finished on 127 laps, 3 laps down.
2.21pm Ron bought 14D in quickly for the crew to check brakes and tyres and went out, nothing changed. I've asked Ron how quick this stop was.
2.29pm 9D in for its 3rd stop and fuel, and top up the radiator as it was boiling. Re-entered the race 10 seconds ahead of 14D.
2:45pm After 4 laps Ron was rapidly catching 9D and 9D blew its engine. From here onwards it was Ron in the lead to the finish.
3:45pm 13D shown the checkered flag.

As you can see the order at 80laps (around 1:15pm) was 14D, 9D, 13D, 23D, 25D, 24D, 15D 1E. Scratch 9D, and take out 23D (busted wheel) and 25D (9 minutes in the pits) and you have:

14D, 13D, 24D, 15D, 1E.

You then have to account for both of the 13D stops at 1.41pm and 1:44pm. One was brake pad changes. We are talking probably 7 minutes all up. Enough for 24D to end up in front of 13D.
Also account for 14D's say 2 minutes in the pits at 2:21pm. By total race time and accounting for the above I get the following:

14D 131 laps.
24D 131 laps.
13D 130 laps.
15D 129 laps.
1E 129 laps.
25D 127 laps.

Now I need to spreadsheet the actual lap times.

All of the above except for the second sentence come from Peter Wherrett who wrote a running diary of the race. Des 100% did the first two stints up to 1.43pm and Ron did the last. There was only 3 x stints for 14D, it only completed 2 pit stops. The one Ron did was a quick unplanned one just to look at tyres and brakes, he remained in the car.

8D and 9D were on the same strategy at their second stops at respectively 12:27 and 12:45 except 9D did pads and 8D didn't, hence why 8D's brakes failed and spent near to half hour in the pits. That is why it ended up finishing at 123 laps, 7 laps down on 13D and 8 laps down on 14D. They were only leading due to the fact they had to complete 3 x refuelling stops, they only had a 1.5 Gallon fuel tank. The Monaros could do it in two stops due to the 26 Gallon tank. This is why both 13D and 14D only did two refuelling stops. Bruce's 3rd stop was only to get Barry out and Bruce back into the car, this was around 1:50pm give or take. The only reason 9D was in front when it popped the engine was because of the quick stop Ron Marks did at 2:21pm. 9D came in for its 3rd stop at 2:29pm, for fuel and water and entered the race 10 seconds ahead of 14D, but 14D quickly caught it and the Falcon blew the engine and limped back to the pits at 2:45pm, this was at the end of its lap 113.

There is no way 13D was ahead of 14D except for the period between 11:17am and 11:30am as Des West pitted for his first stop at 11:17am. West was in front of McPhee at 12:20pm and also at around 1:15pm. 13D did its second stop for pads, driver and fuel at 1.41pm from behind 14D. That is a 6 minute stop give or take. 14D stopped for its second stop at 1.43pm, only did driver change, fuel and one tyre (front right). This is when 9D went in front on 14D. 13D stopped somewhere between 1.44pm and 1:50pm to take Barry out and Bruce get back in. 14D stopped at 2.21pm for a quick brake check, Ron knew his brakes were very limited and knew he was effectively in front as 9D had another fuel stop to do. 9D came in for its 3rd stop at 2.29pm for fuel and water and entered just in front of 14D. In all this, 24D had moved up to be between 14D and 13D as it had only made two stops but the last one was at 12:51pm.