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| | | | Joined: Feb 2006 Posts: 1,867 Shop Shark | | Shop Shark Joined: Feb 2006 Posts: 1,867 | On the yoke end there is a cotter pin that will need to be removed and then you can remove the nut and the yoke should slide off letting the carrier assembly slip off the drive shaft. Hope that helps.
That trannys an SM420. The casting numbers should be on the drivers side near the rear above the PTO cover if I remember right. That would be an original type tranny for that truck.
Jeff | | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | ok thanks very much! That tranny would not have come out of the same vehicle as the 250 motor did? | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | SM420 is the correct 4-speed for a '49 but also could have been original in a '63 to '67 where that motor might have been found.
Last edited by OldSub; 02/19/2008 3:42 AM. Reason: Fixed bad info.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | Just out of curiosity: that is probably not a very freeway freindly tranny is it? So what are my options as far as swapping this for a more streetable tranny- mainly manuals that will bolt up to my inline 250. I have a t350 out of a '78 pickup but not sure if it's any good and not sure if I want a automatic in there or not, but will it bolt up? Thanks for the help guys! | | | | | Joined: Nov 2000 Posts: 1,972 'Bolter | | 'Bolter Joined: Nov 2000 Posts: 1,972 | The SM420 transmission is a heavy-duty 4-speed truck transmission with a 1:1 4th gear - direct drive. The 49 rear end will have a 4.57:1 ratio. So you are correct that combination is not very freeway friendly. It really depends on what you want to do with the truck. Do you want to pull/tow/haul heavy loads or cruise at 65 under a light load? There have been dozens of threads about T-5 trans swaps into this model/style truck. Search this site and the inliners.org site. But T-5's are not heavy-duty......
For help with the carrier bearing go to the links section of this site and look for Keith Hardy's site chevy.tocmp.com for online Chevy truck shop manuals. Good luck!!
Professional Novice
| | | | | Joined: Apr 2005 Posts: 2,102 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,102 | The 350 Auto will bolt up to your 250 engine but you need to consider transmission mounts, cooler & lines, shifter, and of course driveshaft mods. It will not however improve your freeway speeds as it like all non overdrive transmissions are 1:1 in high gear. As Frank mentioned the T-5 is a good option and there are a number of other overdrive options all of which require some modifications to various components and sometimes a substantial cash outlay.
Fred
Last edited by rfs56trk; 02/19/2008 6:45 PM.
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine
| | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | I do plan to use this as a cruising truck and not put it to work. The rear has been swapped but I don't know the ratio it has but knowing who had it, it is probably low. What vehicles had the T-5 tranny? I plan to swap the rear anyway so maybe I'll just see how it runs after that before swapping the tranny. I don't plan to take many trips but I would like to know I could when I choose to. I didn't think about the cooler lines and the other junk that goes with the t350 either so that's out the window. Thanks for the help guys! | | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | The original setup did not use a mount on the transmission. The rear mounts were on the bell housing and the transmission hung off the end. I would think that your bearing troubles probably started there. You probably will want to replace the transmission and probably the rearend with an open driveline. The other approach would be to go back to an older style engine like a 235. I think that you may have a lash up there that will never work properly. | | | | | Joined: Nov 2000 Posts: 1,972 'Bolter | | 'Bolter Joined: Nov 2000 Posts: 1,972 | I was concerned about the same thing when I saw the picture of the home-made crossmember under the tranny and those angle brackets going down to the original bellhousing crossmember. Looked unstable to me. Good luck with it.
Professional Novice
| | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | well on closer inspection the bearing is in great shape, it's the rubber that goes between the bearing and the bracket thats missing that I need to find. What do you think he put the angled brackets on the bellhousing for? Would the extra crossmember really hurt more than help? Last q for today is where is the slip yoke (I think that's what you call it) to where the axle will extend and retract over terrain, heavy loads, etc. | | |
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