Do not know how... Unless you are an expert machinist
the IH 5 speeds always used divorced t/cs when used in full size ihs...
Doubt there is a machined mating surface on the back of the trans that a t/c could attach to... Crawl under one of your loadstars and look at the back of the trans.
Then, there is the probable problem that the d300 bull gear (or any bull gear) will not match the 5 speed output shaft...