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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: dirtynails on May 02, 2017, 01:27:03 pm

Title: 1/2 - 3/4 swap questions
Post by: dirtynails on May 02, 2017, 01:27:03 pm
 I have a 79  C10 swb Custom Deluxe 1/2 ton, 5 lug, 6 cyl, 3 on the tree with wimpy rear gears, that I want to keep forever but I'm getting older and it's getting more and more frustrating to drive due to the manual shift and not being able to do highway speeds for long periods. Anyway, the other day I picked up a 76 3/4 ton, 350, TH-400, C20 Camper Special, 8 lug, with what I was told are 3.73 rear gears, that runs and shifts fine but the body is pretty rough.
 My questions are, is it possible to take the beefier front end parts off of the C20 and install on the C10? What about the rear end, could a guy just uninstall the 3/4 and roll it under the 1/2? I'd like to use the TH-400 and taller gears for sure if nothing else. Also on the C10, viewed from the rear, the hub to hub distance is narrow and looks goofy, the wider C20 hub to hub (wider) distance would look better I believe. Is this a straight across swap out or more issues than I want/need?
 Thanks for any advice and sorry if these are lame questions. I'm recently retired and needed a hobby so I picked this one.
Title: Re: 1/2 - 3/4 swap questions
Post by: VileZambonie on May 02, 2017, 02:48:36 pm
It would make more sense to me to swap in a 700R4 and change the ring and pinion. A lot less work can be done relatively quickly. You could swap over all of the C20 components but not sure you will get the end result you are looking for.
Title: Re: 1/2 - 3/4 swap questions
Post by: Stewart G Griffin on May 03, 2017, 06:13:57 am
What is the end goal?   To have an automatic and be able to cruise at lower rpm?
Title: Re: 1/2 - 3/4 swap questions
Post by: Stewart G Griffin on May 03, 2017, 08:02:12 pm
What is your rear diff gear now?
Title: Re: 1/2 - 3/4 swap questions
Post by: dirtynails on May 03, 2017, 08:33:44 pm
What is the end goal?   To have an automatic and be able to cruise at lower rpm?
        I haven't counted teeth but by tire rotation I'd say I have 3.08 gears. I want to stay a 6 cyl but replacing the 250 with a hotter 292 and hope to gain take off torque but still able to cruise 100 miles at relatively low rpms                                                                                                                                                                                                                                     
Title: Re: 1/2 - 3/4 swap questions
Post by: roundhouse on May 04, 2017, 06:59:07 am
Going from 3.08 years to 3.73 is going to make your engine spin faster, not slower .

Easiest and cheapest way to slow the engine down at hwy speeds is taller tires

Have you considered swapping in a NV -3500 five speed ?

That would give you a lower first gear to help starting off and a Overdrive 5th to help slow the engine down on the highway


Sent from my iPhone using Tapatalk
Title: Re: 1/2 - 3/4 swap questions
Post by: Stewart G Griffin on May 05, 2017, 11:04:55 pm
Going from 3.08 years to 3.73 is going to make your engine spin faster, not slower .

Easiest and cheapest way to slow the engine down at hwy speeds is taller tires

Have you considered swapping in a NV -3500 five speed ?

That would give you a lower first gear to help starting off and a Overdrive 5th to help slow the engine down on the highway


Sent from my iPhone using Tapatalk

X2  This^^^^^

Also, if i remember correctly the HIGHEST gear you could get in a 3/4 ton rear is 3.21 anyways.