I've poured through Chelsea tech and can't find much to assist with. I think your best bet is to contact a local truck shop that handles hydraulics and ask them what model # you would need for your application. Most of the people on ebay selling PTO's have no clue what they have, even when they think they do and it's going to be hit and miss and you might buy 5 ptos before you get lucky.
I have two Muncie 422 NP205 PTOs, one is a direct drive for a shaft and the other is for a pump. Neither pto's helical gear is stamped with a # consistent with thier applications guide. Both gears appear identical but one is stamped 939158 and the other is stamped 34325, go figure... I don't even know if the SP# I gave you before is accurate anymore...