Hi folks, I have an 87 f250 4 x4 with a standard 4 speed transmission. When I put this truck in reverse in 2 wheeldrive and 4high it doesn't engage an sound awful, put the transfer in 4 low and it back right up. The clutch pressure plate and throw out bearing are relatively new. It work fine for a few months but this is now the issue. Any advice on what to check or how to proceed would be greatly appreciated. It also has the 460 in it.

 

From what you describe , it sounds like the problem is in the transfer case and the linkage that controls shifting from high to low range.. If the shifting is done manually check to make sure it is being placed ALL the way into high range. If all appears OK there , the problem is very likely inside the transfer case.