Originally Posted by Car Analogy

Stop going to the dealer!!!

In addition to the non-job they did inspecting it, now they say an intermittent grind in only one gear is the diff? Really? How can that be? The diff is doing the same thing for every gear. Something that happens with only one gear is intuitively something that is only involved in that one gear.

What diagnostics did they perform to conclude its the diff. None. They just want you to throw money at it, and theor competency is clearly as questionable as their motives.

Do the easy cheap stuff first. Adjust clutch rod, change fluid. I am betting this improves your shifts by 99%...