Thanks for the reply, Fred.
I sure have been getting an education on the SM420 this past week. And Tony P has been coaching me through this.
I ordered my gasket set and a new rear seal from Stick Only Transmission Parts waaaaay out there in California. The guy there said there are some differences in the gearsets between the earlier ones and the later ones. So if you go changing out gear sets (as I am doing) the main thing you have to check is the measurements on the 3rd and 4th speedclutch sleeve and the 1st/reverse gear where the shifter forks ride in them -- the "Dog Width." You can match casting numbers on the forks OR (I like this one better) just swap out the entire top cover, shifter assembly and all, along with the associated gearset.
Other than that, he said there wasn't much difference. The gut really impressed me, though. Either he had some sort of reference open in front of him right when I called, or he has the 420 memorized as he just rattled off shifter fork casting numbers to me (not just case casting numbers, but numbers inside the tranny). I was impressed.
Of course, I'm easily impressed... He could have been making the stuff up for all I know about it.
I will be writing up a Tech Tip about this. You experienced guys probably think nothing of tearing into a 420, but it was quite an "adventure" for me and probably is just as intimidating to others like me.
Regards,
John
