just like the title say I've got no 5th or 6th. I finally got my swap done and got a few minor issues fixed but when I went my maiden voyage I find out this problem. The shifter appears to be going to the correct point in it's range to engage but when you let out on the clutch it just makes a mild grinding noise and revs like it's in neutral. 1-4th seem fine and reverse is fine. I checked the old oil when I drained it and I didn't see any paticles or flakes of metal nor did the fluid look dirty or smelled bad. What am I looking at here? mild repair or major rebuild?

 

You sure you shifter is bolted down all the way? I forgot to tighten mine when I did the t56 swap years ago and it didn't like to go all the way into gear?

If not that, then I'd be saying a rebuild is in order. Or at least synchros.

 

You might want to check the synchro thing.

How does it "feel" when you shift into 5th and 6th?

Normall you can tell by the position, it feels like 2 "clicks" when you shift from one gear to another. Example: neutral, 3rd... click click....

Also, 5th, and 6th, are a little tougher to get into. Not nearly as hard as fighting the reverse lockout, but i found, 2, 3, 4, basically shift them selves, but 5, 6, require a little more force.

Just check and double check to make sure you are actually getting into gear. This might be a good time to just support the rear of your car on jack stands, and go for a test drive on your driveway, or someplace where neighbours wont mind.

Not trying to insult you, but you should always start with the SIMPLEST things first. Hopefully its nothing!!!

Being in the same boat (just about to start my maiden voyage), id hate for something like that to happen.