GS6-45BZ variants - differences and compatibility?

Taymar

New Member
May 18, 2022
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Hi all,

I need to pick up a reman transmission from BMW in the near future. I know the unit I want is a GS6-45BZ RWD unit. However, there's at least 5 different variants I'm aware of - but aside from what vehicles they were fitted to, I have no data to compare.

THD4 (earliest? e series n55 cars and the 1M coupe)
THY8 (used in F series cars, _35i models)
THAD (supersedes the other two, nonexchangeable retrospectively for the THY8. Also used in F series _35i models)
SHBT (used in the F80 M3, F82 M4)
SHBS (F87 M2, F80 M3, F82 M4)

I don't have any of these in front of me to take measurements. Eyeballing used units online and the BMW ETK, they look pretty much visually identical; the SHBS and SHBT in the ETK POSSIBLY have a deeper bellhousing, it's hard to tell because the render angle changed.

Anyway - to my question. Since I have to stump up the cash to buy one of these from BMW, I want to get the best version that'll work with my N54. I understand about the male/female pilot bearing situation swap. The guaranteed answer would be go for a THD4 but if one of the others is better/newer and would bolt right up, I want that.

Anyone know if spec sheets exist for these, if they are dimensionally identical, or even if they're all about equal in terms of durability and it's just been gradual evolution? I have nothing to go on?