4T60E model & type identification

[bill buttermore]

I've got a late production (288,xxx for that year) '95 Bonneville non-supercharged with the 3800 with a bad FW2 transaxle. Bought a used one that was shipped from a distant city. The used trans arrived without its riveted metal ID tag, and looking identical to mine but with different (higher) casting numbers on the top and side. The computer plug is the same configuration externally, but the dipstick has a flat black handle instead of the red ring on my Bonneville, and the shift range electrical switch is completely different. It also came with a torque converter that my local trans rebuilder says was only used in 3.4s and 3.1s, so it seems this trans was NOT from a 3800 '95 Bonneville.

The seller says the trans will work fine - all 4t60Es are the same.

All the swap engines and the GM dealer say the only good swap is from a '95 Bonneville non-supercharged with the same gear option.

Will this trans work in my car if I use my old torque converter and my old shift position switch? (They both fit easily.)

How can I tell what trans this is without the ID tag? The guy who sold it isn't saying what its from, just that it will work fine. I have already called the GM dealer who cannot make sense of the various stamping numbers and casting numbers on the used trans.

Thanks for any help.

[Racincc85]

The trans, given that it really is a 4t60e, should work with if you swap out the torque converter and the switch. The only problem that you may run into will be if any of the gear ratios are different, especially the final drive ratio, which they probably will be if the trans was bolted to a 3.1 or 3.4. If you bolt it to your 3.8 the performance of the car might be adversly effected if the gearing is significantly different. what you can do is do a seach on google under 4t60e gear ratios to try and find out if there was a variation on the gearing depending on what car it was used on. If its not a significant difference you could probably get away with using it. If not, i suggest that you return the trans you bought and get the bad one that came with the car rebuild. That would be a wiser choice since you don't know for sure how many miles are on the one you bought. good luck!!!

[bill buttermore]

Thanks, Racincc85,

I wish there were some way I could confirm what the final drive ratio was in this trans with its ID tag gone. I am pretty sure the seller is gonna give me a hard time as he is already ducking my calls, emails and faxes regarding the trans.

[bill buttermore]

Well, I found a stamping on the trans that I was able to decode to reveal that the new trans was originally installed in a '94 chevy. I know from the torque converter that it was either used with a 3.1 or 3.4 engine. The pontiac factory service manual shows different internal electronic connections and mechanical parts for the 4T60E depending on whether it is built for 3.8 or the 3.4.

If the trans would work at all (which is doubtful owing to the mismatched electrical connections), it would not work properly because it was not adjusted for the 3.8.

This trans will be going back to the seller.

[public]

That Sucks.