[kitcarbp]

For my TKO600 built circa 2005, I ran the GM Synchromesh for a few hundred miles and then replaced it with readily available Penzoil product Tremec recommended in their tech literature. It still does not have a smooth 1st-2nd gear shift so its the box not the fluid. Its fine for the street, but would be clumsy if racing in that 1-2 shift since its a bit notchy.