I don't post much here but I have definitely read a lot. I recently started losing 4th gear (large amounts of slip) in my 97 4WD Blazer with 261k miles on it. After some diagnostics I found it was the trans that was finally giving out. So I went on the search for a used trans. I spent a ton of time researching what year 4l60e I could use and found many inconsistencies. Some said 97-2000 would work but something changed in 01 or 02 but nobody had any definite answers. I ended up looking at aftermarket trans controllers for the 4l60e and they all gave a wide year range and that they all use the same wiring. I even looked through the wiring diagrams from 97-2003 and they all matched.

In the end I took a gamble and picked up a 2003 4l60e from a blazer with 100k on it with the torque converter. I also read I needed to get a flexplate for an 03 so I ordered one just in case. Also on the plus side the 03 trans has the deep pan where mine had the shallow pan.

Today I finally did the swap and wanted to make it clear that you can indeed install a 2003 4l60e in a 97. Now my 97 does have the two piece case with the removable bell housing. When I had the two transmissions on the floor I put my flexplate up to the new trans and the bolt holes lined up perfectly. I also measured the install depth on both and they were identical, so I reused my flexplate.

Everything went together perfectly and the trans shifts MUCH better than my 261k mile original. Apparently it has been on the way out for a while.

I'm not sure where the misinformation is coming from so I just wanted to post this and say it can be done.

I hope this helps someone out.

 

Thanks, good information!