Standard transmission

[Derek.Matirne]

Guys, I have a 71 4X4 with the super low 1st, and three more.... I was wondering is a 5 speed out of a, say 89 4X4, bolt right in? Of course I have a manual clutch, and the newer tranny's have a hydrolic clutch, so will the manual work? Thanks guys....

[Mike C]

The NV4500 is neither an easy nor an inexpensive swap. The SM465 that your truck has really works in a wide range of circumstances. It's best to gear your truck to the 1:1 4th gear to get the rpm you want on the highway and take advantage of the low gear when you need it offroad. Even with 3.07 gears, the low range first gear in an SM465/NP205 truck is 39:1.

Compare that to the T150 in my 70 CJ5 where 3.54 gears a 2.97 first and 2:1 in the Dana 20 is only 21:1 low gear.

FWIW, except when needing to go super slow, get started with a trailer, etc. no need to use first. And the 3.5:1 second gear of the SM465 is WAY better than the jeeps stupidly geared 3 speed.

[Derek.Matirne]

I don't use the first gear, pointless to even try.... I haven't had the truck for very long, the few times I have driven it, I start topping out in the low 70's, not really trying to do 120, just would like to cruise comfortable at 75.... Can a guy purchase gears for this particular tranny to make it more highway friendly?

[kwmech]

Originally Posted by Derek.Matirne

I don't use the first gear, pointless to even try.... I haven't had the truck for very long, the few times I have driven it, I start topping out in the low 70's, not really trying to do 120, just would like to cruise comfortable at 75.... Can a guy purchase gears for this particular tranny to make it more highway friendly?

No, you'll need an overdrive, taller gear ratio or taller tires

[Derek.Matirne]

I will be putting on taller tires, what's on there now is some street tires.... I don't know what gears are in it yet, I'm assuming the 3.73, they put them in everything.... I had the same tires on my 72 Blazer with turbo 350, and 3.73 gears, and it flew down the highway.... Thanks for all the info guys, it gives me something to think about....

[special-K]

Is your '71 a K/10 or K/20? If K/10 3.73s are possible. I used to go round and round on overdrive, cost, labor, gears good for off road as well as off road. I finally arrived at just driving 65 and liking it. It's an old truck and it likes it, too. I don't feel I'm running behind with the rest of the world. 65 is getting on down the road just fine. Overdrive is meant to slow the drivetrain down to reduced wear and tear as well as increase fuel economy. But the mass of people are mindless and are just driving faster. I'm not one of them. I just let them fly on by while I enjoy driving a cool old truck

[Dave K.]

My 68 K10 SWB has 3.73 gearing and the 4 speed and 33's. It will be interesting to see how she does on the highway once I get it road worthy.

[my67c20]

So here is some numbers to consider. For every inch in diameter your tire grows you gain 2 mph at a given rpm. For every inch your tire grows you reduce your rpm by 100 at a given speed. An overdrive transmission will reduce your rpm by 600. Changing rear gears to 3.42 drops rpm by 250, and 3.08 by another 250. Assuming these are available for your axle. Estimate gears to cost 1k per axle, or tires 1k per vehicle, or transmission 2k per vehicle, best bet is to go the tire route. Might be a dog off the line, but you have the granny gear, but you gain on the high side. Also with the gear ratio of the SM465, this may give you more range in 2 and 3rd. So @ 2500 rpm the max speed in 1st is 9, 2nd is 16, 3rd is 35, and 1st is 55. With 6" (34") taller tires @ 2500 rpm the max speed in 1st is 11, 2nd is 19, 3rd is 43, and 1st is 67. Just my 2 cents

[Bigdav160]

Has anyone tried a 4x4 NV3500 swap? It's not my favorite trans but it should be plentiful and cheap.

[57taskforce]

Originally Posted by Bigdav160

Has anyone tried a 4x4 NV3500 swap? It's not my favorite trans but it should be plentiful and cheap.

I'd be kinda weary of the 3500. These trucks are a bit heavier than an S/10

[Flying Hamster]

The NV3500 works fine in the 99-06 trucks, behind the V6 and the 4.8, and those trucks are full-size and way heavier than a S-10.
They were also used in full-size Dodge trucks and many jeeps (not exactly a ringing endorsement, but...)