What number tranny?

[gold10go4]

I have a 01 Regal GS with supercharger. Curious as to what tranny I have? 4TE65, 4TE65-HD. 4TE60? Not sure, but I'm starting to think I should find a rebuilt. My tranny was just worked on at the Buick dealer. About 3 months ago the tranny work - some internal part - was replaced. This time the thrust bearing blew up and ruined the tranny. I had an aftermarket warranty, which wouldn't allow the dealer to rebuild, and made them order a used out-of-state tranny. The car only has 75K on it; the dealer thought the used tranny had about 50K, but I don't know. My warranty company is on the hook regardless, since I have a 100K warranty. Silly of them to put a used one in, but that's being penny wise and pound foolish. If it blows, they're on the hook. But I'm starting to look down the road when the warranty expires. I don't want to ditch the car, and might want to have a backup tranny when this one goes eventually. I'm one of those guys who tries to drive a car until it's beyond hope. My cars usually go beyond 200K. BTW the previous repair bill - 3 months ago - was $2,400 - two power window units broken, tranny repair, etc. I paid $100 deductible. This time - tranny repair and "trac on" light problem - $2,500. Only $100 deductible. I'm not a great believer in buying warranties, but this time I bought and it paid off big time. I paid for the warranty about 3X with about 25K left on warranty.

[BNaylor]

You have a 4T65E-HD autotransaxle. GM RPO code MN7.

[gold10go4]

Thanks for your quick response. I'll start looking.

[richtazz]

To expound a bit on Bob's info, your car had a tag code 1XAB variant (the tag is found near the shift linkage) of the MN7, which was an 01 only version, used specifically in the Regal GS and Grand Prix GTP. It has a 2.93:1 final drive ratio (common on this trans for many years/models), but may have subtle differences than earlier or later years with different tag codes. To be 100% compatible, you'll need to find an 01 version out of the Regal/Grand Prix with the tag code mentioned above.

[gold10go4]

What happens if that specific '01 tranny for GS isn't used? I'm wondering if the used tranny the dealership was forced to use is an exact match. What's likely to happen if it isn't? Will it simply perform differently, or will its life expectancy be lower?

[richtazz]

That's what I don't know. The tag codes are model specific, so there is obviously some difference. I only have access to the GM parts computer, not the service side, so I cannot tell you what the difference(s) may be, sorry.

[gold10go4]

Rich,

Thanks for the info. I appreciate it. Gives me something to go on when looking for a replacement.

[BNaylor]

The only 4T65E-HD trannies to stay away from are 2003 and up. They modified the PCS solenoid and circuits. The MN7 autotransaxle used in circa '97 and up GM cars with the L67 Series II 3800 engine are essentially the same with 2.93:1 final drive gearing. All that makes it a HD is the beefier diffential and passenger side axle half shaft. Even a regular 4T65E autotransaxle GM RPO code M15 or MN3 will work and fit. All you need to do is swap out the diffenential which is bolt on and since they all use different final drive gearing. I know of no significant changes or differences between the 4T65E-HD trannies made bewteen '97 to '03 otherwise. However, try to get one with the lowest mileage.

[gold10go4]

B,

Thanks for all the info. You guys are super.