Hi boards, i have a turbo 350 with these casting numbers:

GM27 6260933

can anyone tell me about it? or where to look up the casting number?

 

It's a TH350. What more do you need to know. There's very little difference between all the TH350 produced. There's an odd chance it's a TH375 but very unlikely.

Casting numbers on anything tell very little.

 

a good way to get an idea if the th350 is from a v8 car is to pull the pan and look at the intermediate clutches. you can see them and if there are 2 it probably came from a v6, if there are three it's probably from a v8. the intermediate clutches are 2nd gear clutches. if there are three there will be more clutches in the forward clutch pack also 5 versus 4or3, low reverse 5v.s.4, and direct(3rd)four-which can be upgraded to five with a different piston. Note:if it is a six cylinder th350 that isn't always bad because it has a low planet with deeper gears, and the clutch packs are all upgradeable to more friction material. a pan drop on this unit goes a long way. note: the th350 case is suspect internally as the low roller support wears it the aluminum out. There is a cool upgrade that should be installed in all performance th350's IMO. it uses a bolt in center support that grabs a second set of lugs in the case and a wide 700r4 roller. I don't understand why it is the most overlooked part of th350 rebuilds, as any good shift kit beats the *ell out of this spot. I added a pic.