Posted by Dean in CA [162.158.74.216] on Sunday, March 28, 2021 at 08:25:59 :
In Reply to: Re: 57-68 WM300 NP420 posted by Vaughn [172.68.143.57] on Saturday, March 27, 2021 at 23:39:23 :
The reason for the different casting #'s is the case dimensions are different to accommodate
the NP420 gear set which is not the same as the early synchro M37 gear set. The later M37
and PW NP420 used heavier (stronger) gears.