Is A 4-speed Swap With An Overdrive And Pto Possible?

Well, that's something quite obvious that I completely failed to notice...

By transmission adapter, I assume you mean the PTO that runs off of the Muncie transmissions?

The OD is definitely gonna stay on there, as I want to keep this able to drive on the highways.

I'll be offroading in ID near Boise.

 

With my limited time and money, the Terra gears might be the best choice. I'm already planning on some lunchboxes ($900 front and rear) and the Terras save a good bit of money over the transmission. That would give me more money for sliders, skids, and maybe tires.

 

https://advanceadapters.com/4-jeeps...1*MTcwNjgyMzQzMi43LjEuMTcwNjgyMzUyMC4zNS4wLjA.

https://www.novak-adapt.com/knowledge/transfer-cases/model-18/

A lot of folks jump for a sm420 because of it's "superior" 7:1 low range but with adaptors it is longer than the T18 conversion.

For what it's worth, you may be putting the cart before the horse. See your gonna tear your junk apart if you... as a person, ain't ready. Get the other stuff done and wheel it. You will be surprised at what can be done as-is.
Here's mine, t-90 and a whopping 36.9:1 crawl ratio.

 

I echo the reliable running rig is more important than any mod.
Been on plenty of rides where open/open rigs with less than stellar crawl ratios on 31" tires have done just fine with some spotting and patient driving ( Iron Chest mine, Hole in The Rock, etc.) My locked rig on 33's with 82:1 has also been on the winch line too. Nobody will leave you behind, pack an extra sixer for the help.
Come with a positive attitude and the ability to laugh at yourself and lend a hand.

 

Drive it, drive it, drive it.
Let that tell what you need.

 

Thank you all for your opinions. After hearing from you and thinking some myself, I'll use it as is for a while and see what I need from there.

It is within my budget right now to do a rebuild and terra swap on the D18 and I'd have plenty money for autolockers, maintenance, winch rebuild, skids, and sliders. Is that something I should look into more?

 

For slower speed the biggest bang for your buck and for ease of installation is going to be terra low 3.15 transfer case gears. Low geared 4 speed is much more effective yet much more involved.
For increasing traction the biggest bang will be some form of rear differential. Choose between one of the limited slips or one of the locking differentials. For even more traction you’ll want a front differential traction device.

 

I've already figured out that I'll go with lunchboxes in the front and rear. Eventually I'll put an actual locker in the rear, but for now the auto locker saves me $1k.

 

Jpets 5.17 transfer case gear set was initially intended for early Willys needing super slow gears while retaining the T90 three speed. It’s Totally effective for that scenario. Installation is a bit involved. And will not work if you have a T14 transmission.

 

The only issue here is actually obtaining those gears. Is there a source besides Herm? I tried to buy a set a while back and he wouldn’t sell them. He was rude, pretty much told me off and hung up on me. Bizarre… I’ve been a customer of his several times in the past.

Sorry to digress. Where else can we find the Terra Low gears? I’d love to find a set.

 

They're on Advanced Adapters.

$1093 for OD - https://advanceadapters.com/418315od-teraflex-dana-18-3151-low-range-gear-set-saturn-warnwarn-od-3

$852 non OD - https://advanceadapters.com/418315-dana-18-teraflex-3151-low-range-gear-set-2

 

https://www.advanceadapters.com/418315-dana-18-teraflex-3151-low-range-gear-set-2

 

Huh…interesting. Thanks! I thought AA stopped making them and the supply was bought up. I guess they resumed production?

 

You won't find a more detail oriented guy than Sal @ Vintage Jeeper
https://vintagejeeper.com/products-&-services/ols/products/dana-18-3151-low-range-gear-set

 

Quick update after a couple phone calls.... Apparently this is old news for some of you guys. Of course Terra Flex no longer makes the gears. But after a couple years there is a new manufacturer. ATV Manufacturing perhaps? Anyway, at least there are some reliable suppliers for the actual purchase. I had given up on this.
107:1 Here we come!

 

ATV his Herm.......
I was under the impression that AA was selling the Kits.

 

AKA herm the overdrive gut

 

Yes that’s right. Herm is manufacturing them new through his company and using AA and apparently others as distributors. I feel ok about giving a credit card number to a reliable distributor. Too many horror stories lately trying to go direct.

I just didn’t realize these were available again.

 

Herm's business has always been ATV manufacturing.
I would be willing to bet that Herm bought the rights to the Terra Flex gears and he is having AA manufacture them for him.

 

Yeah I realize that Kyle. I talked to the AA tech guy and apparently they are only a distributor. It seems ATV/Herm is having them made somewhere. He didn’t give me details on who’s actually making the gears. Sorry on the confusion.