Finally! (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Mar 27, 2003
Threads
358
Messages
6,437
Location
Georgia Tech
Well, finally laid my eyes on an SM420 today. :D

After ~ 2 years of trying to find one locally for a reasonable price, or even one to be shipped, I finally broke down and just bought new. :D

I know Butch was somewhat doubtful that the NOS SM420 was a reality, I figured I would post up to confirm it is. Only catch is that you must find a civilian top plate as the military one is set up for some kind of remote linkage. Military surplus trannies also do not have a PTO opening. Not really a big deal, but I was planning on trying to mate a SM420 PTO to a Ramsey or Toyota winch drum. Oh well. :rolleyes:

Tranny even came wrapped in 40 year old oiled cheesecloth, all shafts had original protective sleeves, and the best part is I don't have to fawk with cleaning and painting it.

Tranny - $325
Shipping from Cali to GA- ~$75
Top plate plus shipping- $75
CIMG0236 (Small).JPG
CIMG0237 (Small).JPG
CIMG0238 (Small).JPG
 
Post up who you purchased it from....


8274-50 is in your future..... ;)



Good luck!


-Steve
 
Oops-

Antelope Valley Truck parts
http://www.avettruck.com/
Gotta call. Ask for Steve. Great to deal with. Ordered it one week, had it the next.


I know, I know. Just waiting for a deal to stare me in the face. :rolleyes: Probably wait for another year and then break down and buy a new one. :rolleyes:
 
My 3spd toyota shifter.

Supposedly works without a problem.

4spd shifter can be used, but the bottom part that moves inside the gates must be lengthened.
 
will the 3spd shifter work a sm465 as well or just the 420?
 
congrats bailey....looks good


malphrus
 
Jim, I was dissapointed when I first took a look, as I can't find a serial number that corresponds to the one civilian 420's have that can be decoded to find build date. I'm not sure what time period Gamma Goats were built during, so I don't know exactly how old the transmission is. Supposedly they are the same as the later 420's aside from the wonky top plate.
serial plate.jpg
 
CruisinGA said:
Supposedly they are the same as the later 420's



You are correct with this info.


I purchased two of them in SLC back in 1995. Still have one, and sold one to Jimmy V... ;)



Should work good Bailey.



:beer:
 
do make sure you have the right top plate for that tranny. I think there were atleast two varieities.
I would drill a hole and thread it where the PTO cover would have been so You can fill and check the oil level. Its nearly impossible to get at the fill plug once the t-case is attached.

Pretty cool!

Dustin
 
The GammaGoat was an odd thing. Six drive wheels. Some were designed to be driven normally and others were made to couple with the other type backward, hooked up back end to back end like some train locomotives do. So the normal kind had four forward gears and reverse while the other type had four reverse gears and a forward.

We assume you bought the trans for a forward driver, not the pusher?
 
honk said:
We assume you bought the trans for a forward driver, not the pusher?

We'll assume that until I discover otherwise :D

Whatever gear the tranny is in right now, is a forward gear. haven't tried to shift with the wonky linkage.

Should work good Bailey.

Thanks Steve, hope so. Really looking forward to getting this in. Sooner I get it in, the longer my clutch will live. :D

Steve- can you confirm as to whether or not the 3spd shifter will work?

do make sure you have the right top plate for that tranny. I think there were atleast two varieities.

Do you mean a variety other than the last year ('67) top plates that had a reverse switch installed unlike all other years?
 
If you have a late 420 top plate with the back up switch installed, it should work, just like the earlier ones would.


Yes, the Toyota three-speed shifter cane works just fine in a 420 top plate. That is the way mine is set up.


Good luck!


-Steve
 
Poser said:
If you have a late 420 top plate with the back up switch installed, it should work, just like the earlier ones would.

Unfortunatley my top plate does not have the backup switch. Just wanted to see if there was a difference in top plates over the years aside from that switch.


Thanks!
 
Not sure how many of these are out there. I bought/installed mine sometime around 2001-2005 (I don't even remember). As I recall it was was virtually new, never having been used, and had a special coating applied to the gears and seals for long-term storage and preservation. The Contract Number dates it back to 1982. It has run beautifully for me. I'm no expert of the Munsey transmissions, so I can't comment on how it differs from other SM420'sor the SM465. I don't recall making any modifcations other than using the 3 Spd Bell Housing. I have read that the SM420 input shaft is a few mm shorter than the Stock Toyota transmission and that you need some kind of input shaft bushing and a bushing spacer, but I don't recall ever adding any such modifications, and I have nver had any issues with the Pilot bearing or clutch.
 
These seem to be off the M561/M792 "Gama (or Gamma) Goat" 6-wheel drive semi-amphibious vehicle (15,00 made) and the M792 ambulance truck variant featured additional seats that could be folded out to make a bed for the wounded, a heater to warm up the rear carrier module, and a canvas roof to protect its passengers from the elements. The M792 was deployed in the Invasion of Grenada which took place in 1983.
 

Users who are viewing this thread

Back
Top Bottom