Click on image for the lowdown. 
====
| | | Forums66 Topics128,180 Posts1,057,153 Members48,464 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Aug 2005 Posts: 19 New Guy | | New Guy Joined: Aug 2005 Posts: 19 | I have a 1954 3600 that has a 68 307 in it. it was installed in the 80s with the the original SM 420 transmission ( 235 block cracked ). been playing whack a mole with 307 and have very limited time to work on it, isolated a rod knock on #1 cylinder and decided that its time for a new motor . a new chevy 350 crate is here with assorted parts , front end of truck is off and engine parts are disconnected . the question is should I pull engine and transmission together? which looks quite tight given the the way the SM420 sets behind that crossmember or pull engine and leave the sm 420 in place ( with extra support of a transmission Jack ) ? or remove sm 420 then lift engine out ? any hard won experience to share here  Brice | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Probably easier to remove 420, then pull engine.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Feb 2004 Posts: 29,875 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,875 | If you're just changing the engine, there's no reason to mess with the transmission, or even unbolt the rear motor mounts. All you'll need to remove is the starter since it bolts into the bellhousing. My 59 Suburban had a 283 that I replaced with a 307 that way. All the bellhousing-to-engine bolts are accessible on a V8, not buried behind the flywheel like on a stovebolt six.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | With the v-8 engine in there you should be able to un bolt the engine from the bell housing & swing it right out. Support the trans like you said.
George
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Aug 2005 Posts: 19 New Guy | | New Guy Joined: Aug 2005 Posts: 19 | after close inspection due to the way the motor mounts are designed , it appears the motor sets straight down on them and you can't remove the motor mount attachments from the motor without actually pulling the the motor due to the custom boxed motor mount frame connection, previous owner did this in the 80s and he did very good quality work so I am not messing with the frame mount supports .
this means out pulling the transmission appears the optimal way to do it. | | | | | Joined: Nov 1995 Posts: 5,744 24601 | | 24601 Joined: Nov 1995 Posts: 5,744 | Pulling the 420 isn't that hard. Even I can do it unassisted and without causing collateral damage. 
~ John A kid raised on Hotwheels, Matchbox and Tonka cannot be reasonably expected to own only one vehicle as an adult. 1949 Chevrolet 3804In the Legacy Gallery | In the Gallery Forum1973 IH 1310 Dump1963 Kaiser M38A12001 International/AmTran RE3000 "Skoolie"2014 Ford E-350 4x4 (Quigley) | | | | | Joined: Aug 2005 Posts: 19 New Guy | | New Guy Joined: Aug 2005 Posts: 19 | it looks pretty straight foreword .
it appears on this 54 3600 to drop the drive shaft , you need to undo the U clamps at transmission and rear axle along with the support bracket for the front propeller shaft bearing support . is that correct ?
thanks Brice | | |
|
|
