[chevycc1970]

I recently did the same thing yes you do have to get a 4 speed to a NP 205 transfer case adapter which are not hard to find they used the same one up into the mid 80's. your transfer case is a 27 spline and your SM 465 will be a 10 spline. You and buy that adapter sleeve from Off Road Design that is 10x27 spline part# GU4011-A and you will be in business and no need to change input shaft on the transfer case.