1965 c10 ratio gears...swap..fitting help!!!

[Vincentnova]

Hello
I feel like i cant find any precise information about it
I have a 1965 c10 4speed low gears
Never use the fisrt gear
All original
And like most know on highway....60 mph engine screaming loool
Im pretty sure i have 4.11 at the rear end..
Well i dont want swap rear end
And dont want swap tranny either

What kind of rear end are those ?
Where can i find gears ?
Im between 3.42 and 3.08
Can i find a set of gears that could feet the actual diferential ?
If no please let me know what to use and where to look
Thanks

[Clyde65]

Your 12 bolt will be a series 4, mean 3.73-4.10 ratios only.

To get the rpms down to non screaming, your going to need to do one of the things you don’t want to do. The 5speed swap would be an awesome swap, but there is more than just the trans swap. Do a search for 5speed swap and look that over.

With your 4 series carrier, 3.73 will be the lowest ratio you can go without swapping the whole rear end housing. So you may consider just finding a 12bolt 3 series with a 3.08 and rebuild with new bearings, seals and 3.42’s as well.

Good luck!

[Vincentnova]

Ok
And those 12 bolts serie 3 , where i can find it ? Wich car or truck ?
Is it a direct fit or need welding ?

And or ? About the 5 speed ? Wich one exactly from wich vehicul?

[Clyde65]

63-72 are direct fit. Coil or leaf.
70 and up will be 1.5” wider but that’s not a problem.
73-84(?) 12 bolts will work, you just need to change the leaf/coil mounts. They are also 1.5” wider.

5speed: Best option out there but not the cheapest.
http://67-72chevytrucks.com/vboard/s...d.php?t=482069


Good luck!!

[Captainfab]

You can install any gears you want into your 12 bolt housing. You just need the correct series carrier. This would be the perfect time to up0grade to a posi. However if you do not have experience with setting up differential gears, that is best left to a professional.

The easier option would to to find a '65-'70 truck 12 bolt with the gears you want already in it. If you go with a 3.07 gear, you may have to start using 1st gear on take off from a stop.

[Vincentnova]

Yeah i would love to use the first one..
Always feel short to drive only 3 speed manual

[Captainfab]

They way GM originally intended the SM420, SM435 and SM465 to be driven during normal driving is to start out in 2nd gear. First gear is intended for getting very heavy loads moving or off road crawling at slow speeds. This is why they are most all geared the way they are. These trucks were intended to be used as trucks and engine RPM and highway speeds were not a concern.

Originally Posted by Vincentnova

Yeah i would love to use the first one..
Always feel short to drive only 3 speed manual