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| | | Forums66 Topics128,088 Posts1,055,998 Members48,430 | | 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!
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on the Internet for over 30 years! and not clogged down with Ads! Again, thanks! | | | | Joined: Jan 2016 Posts: 11 New Guy | | New Guy Joined: Jan 2016 Posts: 11 | New bolter here.Just bought a 46 CC303 with a 270 and 2 speed axle. In the early stages and hoping for a lot of help from you guys. Planning to upgrade trans to a St10-t5 but also thinking I need to change the rear ratio but want to keep the 6-lug wheeled dually.If I can change the pig great, if not, is there a 1 or 3/4 ton axle that will to the trick? I hope there are some experts out there. Thanks in advance, Mike | | | | | Joined: Jan 2008 Posts: 4,961 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,961 | A CC 303 would be 1942 model that came with a 236 with a single speed rear. It looks like someone has already did some upgrading. You need to try to identify the 2 speed. It may not all that bad of a ratio. A 1946 model would EC303. | | | | | Joined: Jan 2016 Posts: 11 New Guy | | New Guy Joined: Jan 2016 Posts: 11 | Thanks, The tag reads CC-303, its 160" wheelbase,the serial number on the tag is 48324 which is in the 46 series. The engine and head number match a 46 270. Don't know whats right or wrong just what it says. Where do I find the number on the axle and is there a table to tell me what ratio it is? Thanks again, Mike | | | | | Joined: Jan 2008 Posts: 4,961 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,961 | According to the master parts book, a CC303 is a 1942 model @ 160 WB. However, parts books are not always correct. Apparently you have what you have. A 270 is not listed to be offered in a 303, but it could have been a government or emergency vehicle that was specced with a 270. You probably have the 1350 2 speed. It would probably be 5.83/8.10 or it could possibly be 5.14/7.19 which would be a good ratio. It is hard to tell because the truck you have does not conform to the master parts book. | | | | | Joined: Oct 2012 Posts: 60 Shop Shark | | Shop Shark Joined: Oct 2012 Posts: 60 | I'm in Wisconsin. Have a 1946 CC302. 1.5 ton with a 134.5 wheel base. My axle is a Eaton 1350 two speed. If you get rid of yours I might be interested in buying your 1350 as a back-up. Mike | | | | | Joined: Aug 2006 Posts: 129 Shop Shark | | Shop Shark Joined: Aug 2006 Posts: 129 | I don't think the S10 T5 is a good fit for a large truck. They are not known for their strength. Would probably be ok really watching it, but it may be worth checking around before you go through the trouble to make sure it is not going to grenade! | | | | | Joined: Jan 2016 Posts: 21 Wrench Fetcher | | Wrench Fetcher Joined: Jan 2016 Posts: 21 | I would tend to agree that the S10 transmission is a little "light for our big trucks. It is not the horsepower that will lead you to breakage it is the weight. I would look for a bigger truck overdrive unit. As far as your axle the "high gear" (lower number) of the rear end might be alright. I would check the rear end for numbers stamped on top of the center section (normal Eaton MO) and google them.
Proud caretaker of U.S.A. truck 3219442-S 1943 Chevrolet Cab Over Engine 1 1/2 Ton 4x4
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Check your 2-speed ratios(most default to low gear) so you know where you know to go. I agree T-5 too light.
Ed
Last edited by EdPruss; 02/15/2016 5:10 PM.
'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: Jan 2016 Posts: 11 New Guy | | New Guy Joined: Jan 2016 Posts: 11 | Thanks for all the great input Guys! Having fun and learning a lot here and my own. I misspoke... all the wheels are 5 lug. (brain fart). I will check on the axle numbers.
All the body parts are off to get blasted and primed. I have engine torn down and head off to be reworked.
So the plan is to convert this into a "big bolt" pickup. Im getting rid of the extra 1/2 ton helper springs and shortening the wheelbase from 160 to 134.5 and building a 9' bed. So the direction is lighter duty. May still go to a smaller lighter rearend...but keep the dually...I would like to move to a more modern 5 speed syncro trans...if the T5 is too light then maybe the NV3500. Does anybody have experience with adapting an NV to a 270?
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Some NV's come with integral bellhousing, won't work. There is a gentleman on Inliners int'l that makes an adapter plate for B-P-O Cad GM to use a modern GM bellhousing, easier to use, Need to make new pedal mount. Have one on my 302.
If your bolt pattern is 5/10, then there are modern rear axles with that- D-70/80, 19.5 wheels work fine, however, may look undernourished if yours came with 20's. 22.5's look OK, hard to find, look on '50's farm trucks.
Ed
Last edited by EdPruss; 02/15/2016 5:20 PM.
'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.
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