On my 1988 mercury 70hp, when I put it in reverse, it is OK when idling in reverse, but when I increase throttle, it jumps out of gear and makes a grinding sound. I have tried adjusting the shift arm but it still does this. Thinking it is the lower unit, I purchased a used lower unit and plan on exchanging mine. I found out on this forum that there is no shift linkage to the lower unit. So now my question is: Is it the lower unit or something else? Anyone? Thanks to all that helped me by answering the question on the removal of the lower unit. It is great to have people help you out on these forums, even though a question has been asked a million times.