3rd gear slips...help....
If you would like to tell me moe or discuss feel free to post back here or give me a call
Hope this helps though it be bad news I am sure
Either one of the possible causes are going to be internal.
We build 4L60E's for Trucks and Suburbans often. Call me and I could spell out some options you may not be aware of.
Good Luck with it!
g







