[Rocky Rotella]

Originally Posted by Brock1030

So, no other way to determine if the unit is a correct UH code, save the production stamp and the VIN number on the transmission case, correct? Kindly advise.

That's correct. Unlike Muncie where the UPC was denoted in the stamping, Warner Gear didn't do it that way from a production standpoint. It used machined grooves on the input shaft. Warner Gear did produce complete Super T-10 units (as well as various internals) that it sold on the aftermarket under its Power Brute line. Those were essentially the same second-design Super T-10s that GM used in its production vehicles, but they included a number-904 cast iron main case and often (but not always) high-nickel 9310-alloy gears. These aftermarket units had an identification tag affixed to one of the bolts securing the side cover.

And if I can confuse matters for you (!), some of the 1979 F-car production transmissions with 3.42:1 gear ratios included the number-904 cast iron main case. While these are sought after from a durability standpoint and some believe that GM used them to ward off warranty claims with the deep gear set, I spoke with some Warner insiders while gathering material for my book and one former Warner Gear employee believed that GM simply chose the cast-iron case during this period as a way to save a few pennies since casting iron was cheaper than casting aluminum. Is that true? Until we find a vintage Pontiac (or GM) document that conclusively explains it, I have no way of knowing.

[Rocky Rotella]

Originally Posted by Brock1030

Interesting though on this SR block, as it is not the later XX481988 block, but rather the earlier 500557 - pic attached. This car was sold Thanksgiving week in 1978 in Houston. When the failure happened, I surmised that perhaps the SR blocks available at that point in 1979 may have only been these earlier blocks or that they were using up the older SR stock W72 blocks first - any thoughts on that point?

I can't begin to guess why Pontiac didn't supply your Trans Am with SR XX481988 block for the warranty claim, but now that I think about it, I also can't ever recall ever seeing one. That doesn't remotely suggest that SR XX481988 blocks don't exist, however!

Another possibility is that since Pontiac's last 400 block castings were produced in late November 1977, they prematurely exhausted the supply of SR XX481988 fitted block assemblies they produced by that time or that all XX481988 block castings were used for production vehicles.

Regardless, it's quite interesting to note that your block in an SR 500557 casting. I wouldn't have any concerns about its longevity or durability in your particular application. And speaking of that, your car is looks stunning!

[Brock1030]

Originally Posted by Rocky Rotella

I can't begin to guess why Pontiac didn't supply your Trans Am with SR XX481988 block for the warranty claim, but now that I think about it, I also can't ever recall ever seeing one. That doesn't remotely suggest that SR XX481988 blocks don't exist, however!

Another possibility is that since Pontiac's last 400 block castings were produced in late November 1977, they prematurely exhausted the supply of SR XX481988 fitted block assemblies they produced by that time or that all XX481988 block castings were used for production vehicles.

Regardless, it's quite interesting to note that your block in an SR 500557 casting. I wouldn't have any concerns about its longevity or durability in your particular application. And speaking of that, your car is looks stunning!

Thanks so much, Rocky. Very interested in your SR block studies and any sense that can be deduced by those numbers associated with each one. Also, very glad to know about your book on second generation Firebird-T/A’s , which I will order, noting you have several other titles compiled as well! Thank you for all your dedication to recording the history of this great mark for many future generations. Also, will obviously assist with restoration work. I used just such resources that were invaluable in my past restoration projects, namely a ‘64 Austin Healey Mark III BJ8 Phase I car and another such resource for a 1970 Olds 442 convert project - pics attached.

Thanks again, and let me know if you hear of a 1979 Pontiac Super T-10 transmission for sale that would be correct for my car. Thanks, Rocky.