After blowing wheel cylinder after wheel cylinder in my drum front and rear jeep I decided it was time for a switch of axles. Since I know the toyota axle will hold up I chose to go that way. My jeep has an SM420 in it and it was adapted to a Spicer 18 which is for an offset rear axle. When I switched to the toy running gear I went to a centered rear diff, requiring a change of transfer case. I could have swapped to a model 20 but the options aren't any better than the Spicer 18 for gearing.

I decided to adapt a Toyota pickup tcase to the SM420, with the popularity of the toyota parts there is no cheaper way to get low! By adapting to the toy case I can run dual cases, or 4.7 gears in the tcase, or even dual 4.7 cases! The options of gearing with the toyota case are the best there is.

The Marlin Crawler SM420 adapter was introduced as the "ToyBox" and was meant to mate the toyota reduction box to the land cruiser tcase to be bolted behind a SM420. My jeep is the first to run just the toy case alone, and this setup could be used behind the toyota trucks with an SM420 (there is an adapter by OTT to go from the toyota 22r to the SM420) utilizing the 7.05:1 super low first gear!

Installation of the adapter consists of replacing the male input of the toyota tcase with a female, bolting a plate on the SM420 and a retainer, and bolting a plate on to the toyota tcase. Then the two plates are bolted together for an overall adapter thickness of less than 2"!

Here is what you get with the kit, a machined reduction housing with female input gear, 2 billet plates, SM420 mainshaft retainer, all necessary hardware, and the crawler knob

Step 1: Assemble Transfercase

In order to install the new reduction housing the toyota transfer case needs to be dis-assembled. The toyota transfercase is actually pretty basic, and although replacing the reduction housing requires a complete tear down don't let it intimidate you!

First remove the 30mm nut holding the driveshaft flange on and remove the flange itself.

Next remove the centersection by removing all of the 14mm bolts facing the rear of the transfercase. If your case is a leaker you may want to remove the smaller "teardrop" part of the case but I opted not to as it is not necessary.

Here the center back part of the transfer case is removed.	Here all of the components of the mainshaft are removed	This is the new input (above) along with the old low range gear and shift fork in the newly machined unit.

Next all of the components on the mainshaft can be slid off, be careful not to lose the ball bearing. There is a cast retainer on the mainshaft with 4 12mm bolts that can also be removed.

Now you can flip the transfer case around and remove all of the bolts holding the reduction housing on and it can be slid off.

The reduction housing will need to be returned to Marlin Crawler as a core part. At this point you will simply put the case back together with the new input and reduction housing.

Here you can see the 10 spline female input gear installed	All genuine Marlin Crawler products are numbered, mine is number 6 but the first to go in a Jeep and the first not to have a land cruiser tcase bolted behind the reduction housing I am told..

Step 2: Install Retainer

Although it is a small and easy step I imagine it is an important one - so your transmissin stays in gear!

The retainer slid right over the shaft coming out of the back of the transmission and was easily tightened with an allen wrench.

Step 3: Install Plates

One plate will be bolted to the transfercase and one to the transmission itself, and then the two will be bolted together.

Here the one plate is bolted to the transmission	Here the other plate is bolted to the transfercase

Additional Requirements (stuff that doesn't come with the kit)

2 major things will be required, a crossmember and drivelines. It will also be necessary to drill a hole for the new transfer case shifter - or shifters if you decide to run a twin stick, which is just one of the many "goodies" out there available to you once you make the switch to the toyota transfercase. More than likely your running a speedometer, which means a custom cable to go to the toyota transfer case. I was able to have mine modified for just $6!

I am not sure how the dana axle is but toyota flange at the diff was offset a few inches so the driveshaft will not exactly be straight which sounded strange to me at first, then after looking at other vehicles it is pretty common.

The rear output on a toyota transfercase is much higher than the Spicer18 which makes for more driveline angle, I compensated by extending my wheelbase. I believe the output is similiar to a model20 transfer case.

Here is the custom crossmemember made from flat plate and straight tubing	Here it is installed and you can see the two plates that make up the adapter

For more information and the land cruiser applications see the marlin crawler web site at www.MarlinCrawler.com

Marlin Crawler 1543 North Maple Suite B Fresno, CA 93703 (559) 25-CRAWL (559) 252-7295 Fax (559) 252-7294