well after looking at some of the b series tranny ratio sites, it said that the ys1 has a 4.4 final drive but looking on those acura parts websites shows that the ls hydro and ys1 cable trannys have the same part number. does anyone know for sure 100% which final drive the ys1 ls tranny has?

 

ys1 is a 4.4 final. All hydro parts are swapable into a ys1 case.

 

so its possible to put a ys1 4.4 final drive into a hydro 4.2 final drive ls tranny?

 

yes