I have a 1980 cj-5..it has a 258 ,T-176 trans ,dana 300 t-case ,3in body
lift and 33x12.50 tires. No matter where I have my t-case shifter (except
neutral) it seems like it's in lo gear (i'm in 4th gear by 15mph). ANy
advice would be appreciated
I don't know of this will help or not but; there is rectangle shaped cover on the bottom of the 300.
Remove this cover and look up into the case, you will see two rails and on the rails there is a set screw for each. It is possible one of the set screws(alen head) on one rail came lose not allowing you to shift out of low. Like I said I don't know for sure if this is your problem but it is easy to check.