Speedometer Gear Housing Differences

[kdml]

I picked up a new speedometer driven gear to try to get my speedo to read accurately (see earlier thread here:http://67-72chevytrucks.com/vboard/s...d.php?t=642420)

Along with a new driven gear I purchased a new gear housing as I am going from a 42 tooth gear to a 39 and it appeared the housings are different (at least based on the website I purchased the parts from). I purchased from PATC part number 54 (see here:http://www.transmissioncenter.net/sp...n_______va.htm)

I tried to install the new housing in the transfer case and it is too big. The original housing is a little under 2", the new housing is a little over 2".

Are there different size housings? Since I purchased a housing for a 700r4, but am installing in the NP208 t-case, do I need a different housing for the NP208? Do I really need a different housings or can I install the 39 tooth gear in the housing for the 42 tooth gear? Just trying to gather a better understanding, before I contact the vendor

Thanks