http://www.marlincrawler.com/htm/transmission/5a.htm

I'm looking at the second option of the R-series upgrade.
Anyone done this? The 5.15:1 1st gear ratio
would be awesome. Just wondering if it's as good as it sounds.

 

its really not needed. the first gear for a daily driver will be useless and overkill. stay with the stock gearing cause there really isnt any reason to lower it more that it already is. I once thought about it too but decided against it because of the lack of need for it, plus youll save money for other mods

 

Yep. I did it. Combined with the heavier flywheel it makes for a much easier to wheel rig. And now that I am running much bigger tires, it also helps off the line too.
But I put over 75K miles on my 4Runner with that gear set, stock 4.56's and 32's. Great combo for mild wheeling and a lot of highway miles.
I would put in my top 10 best mods on my rig.

 

Thats good to hear, because it seems like it'd be
well worth the money.

You're right, fillsrunner, it would be overkill on the road,
but for how often I drive it as opposed to my Tundra,
it wouldn;t be too bad.

I'm just thinking of this option due to the lack of
ability to re-gear the V6 chain drive tcase.

My only real worry here is the possible
downgrade in quality and dependability.
I know that MC does quality work and uses only
thebest components, but the R-series trannys
are near indestructible in stock form.

 

Ya I hear ya about the chain case and the lack of ability to change out the gears. They do however hold up quite nicely. If you look around craigslist and stuff you can find redution boxes and also full gear driven cases for cheap. My buddy Eric found 2 for $50 and sold me one for $25.

Ide almost say get s reduction box with some 4.7's and keep the stock chain case. Just an option. Ive heard other not bad but not neccicarly good things about the 5.15:1 gears in the tranny. I cant think of it right now and why but I know Ive heard it somewere. Im sure eitherway you go will work out just fine for what you want