I am in the process of preparing my engine and trans for installation back into my '95, and I wanted to see if I could address the slip into TCC lockup that I felt when I test drove my "new" used trans. I intend to change out the turbine shaft seal for sure, will probably swap torque converters, and if it is not too difficult I am toying with the idea of changing all the turbine shaft seals and maybe swapping the TCC and PWM solenoids from the old trans..

I spent about 20 minutes with the parts guy who was kind enough to give me printouts, part numbers, and prices for these parts for my '95 SLE. They clearly show a PWM solenoid (8683535: $75.64) for my trans. A PWM solenoid is also shown and described in my '92 FSM. So, I still don't know what makes the '95 Bonneville a "year and make specific trans," but I don't think it is the use of the PWM solenoid.

I do believe that the trans cannot be swapped with others successfully for a simple reason. Honest junkyards will tell you that it is this way. The Car-Part.com search engine will also show you this when you search. These are the people who stand most to profit from interchangeability, and they will not recommend it. We would just like to know WHY we can't do it! Or what we need to change to make it work.

i think that it all comes down to matching up the # from the orignal trans to the new one. If they match they you have a winner, anything else is up to chance. I think alot of smaller people/parts yards dont know about the interchangeability of the trans.....

every trans with a different model number has slight variations on what is used inside of them. for instance, on the L60, it can change the following:

valves in valve body
input shaft
torque convertor
stator shaft
output shaft
reaction carrier
input carrier
bell housing
boost solenoid
boost sleeve

and that'* just off the top of my head. there'* also different band apply servos, and things of the like. and i'm sure there are things that after almost three years, I still don't know about. It would take a good long time to make a list of everything that'* different between models...

that would be huge

yup. kind of helps to explain how the same transmission that is in an H2 is in a corvette, huh? They're technically the same trans, but the similarity ends somewhere after the powerflow and how it works...

i'll see if i can dig up a list of what was different on those years for the t60, but don't get your hopes up...

I know that finding info on the 60 and the 65 is a hugh task, the trans and the info is like a secret at GM

i have no problem with secrets, the problem is with age

a lot of the stuff that was done in 95 never found it'* way to the intra-net... they weren't nearly as computer dependant then. so while it'* possible that the records are out there somewhere, there'* always the possibility that the information you want to know is on a single piece of paper in a drawer in some guy'* cabinet that hasn't been cleaned out in 4 years...

that'* the most challenging part. stuff from about 98-up is easier to get a hold of - a lot of it is on the intra-net. not all of it though...

the quick search yielded this info for the 99 t65. gettin closer...

RPO Difference:

M15: 245mm torque converter

MN3: 258mm torque converter

MN7: 258mm torque converter and heavy-duty gearbox

now keep in mind, generally speaking, a different torque convertor means a different stator shaft and input shaft, depending. this info was part of a broad overview. i'll see if i can get more detailed info...

You bet! Knowledge is power. I would appreciate learning more. Thanks, Don.

I know for an unquestionable fact, that a '94 transmission will work in a '95. I know this because I have a '94 4T60e-HD in where my '95 4T60e-hd should be. Mines from a '94 L67 car. Hooked right up. Working great!