not sure what or how the "kit" will be but maybe as i said,, a ford 9" (Housing being made now) to BOLT into the crossfire as the mb diff. does now ,,,and a 1 piece drive shaft that is a bolt in and of course axles that would fit the crossfire
1 kit = 1 ford 9" diff with whatever gears you want.
-----1 tcu set up for the gears you choose .
---- 1 one piece drive shaft
-----2 axles

don't ask the cost,, we don't know once the first one is made we will know,
I have funded the r&d will keep you informed. jim