Hi, can anyone explain why I would have a SLR5000 HT engine block that has only 4 numbers after the HT rather then the 5 numbers which is the norm, or has there been a number missed when it was stamped

any help is apprecciated

Why did LH/X get different block letters when they were still the same motor etc??? only maybe the air cleaner/ alternator/ exhaust would of been altered? but the block & heads, carbie etc were the same????

Maybe the 202 manual in the ADR27A LX UC do not have EGR ?
the HX 5.0 L manual does not have EGR ? is that true. as she did not need it and maybe the light torana passed as well ?
A mate claimed his 202 4SP did 185 km/h flat out, i would no belive it but a mates mum had a VB 202 auto and it did 185 KM/H to, and i was following along behind him and seen it to be true but another mates 202 VB auto only could do 165 KM/H.
So how is that ?
There is a smaller cam in the manual 202 to the auto's.
Maybe some manuals get the auto cam by mistake all diff rations were 3.08 totaly stock cars but the auto that did 185 was slower of the mark but once it got going she flew. maybe it's the timing gears as well being more advanced or retarded and the wrong one picked up and put on.

As far as I am aware all ADR27A V8 manuals had no EGR valve on them, just a blanking plate. The ADR27A 202 autos are atually a higher performance engine, they have a bigger cam in them than the manuals which I think are the same cam as the earlier 202's. It doesn't really explain though why the auto LX-UX ADR27A 202 engines used HX-HZ engines with an X added at the front at the assembly plants (for LX) eg XQL876543 or XZD9876, whereas the manuals continued with a HL engine with a number that existed in the LH Torana number sequence. If it was important enough to make the LH engines and the rest of the LX and UC engines have their own prefix and number sequence why not simply make the auto engines HL also? HX and HZ's don't get anything different to the 202 manual's QL (later HL) or the 173's QD (later ZD) to make them obviously an auto engine. So why do it to the Torana 202 auto?

Note that the cam listed for the LX ADR27A manual engine is the same as all pre ADR27A 202 ie 2818929, also the same as HX/Z manual. The auto ADR27A cam is 9930127, same cam as auto HX and HZ.

I have a feeling GMH knew they'd hit 999999 in the HQ sequence so decided to give LH it's own sequence. That or they knew the V sized cars were coming (VB on) and intended to continue the Torana sequence into Commodore, but when it was decided to make all Toranas the 4cyl "size" vehicle (they all became a U sized vehicle at the start of UC) and since the new V sized Commodore was a whole new thing they then started a new sequence for those? Just speculation.

The reason for the X is to show the engine was in an LX, not a HX. And it is a HX engine, not an LH-LX engine. The quandry is why did they use a HX engine and whack an X in front, why not simply make it HL and use a Torana number like they did on teh manuals.
XZL is a red 202 and hence has red rods and red crank. It is the exact same application as XQL. The Z is there simply because the Q sequence reached 999999 so it rolled over to Zx1001.