Looking to dual case my '85 extended cab truck. 5 speed manual, top shift case, 22re, SFA. So do I need another top shift shift case or a forward shift case? Obviously i need the adapter plate as well. Are there any guides on doing this project? As in a walk through kind of thing. I cant find any info on which cases are useable or better to use versus the other.

 

You'll need to modify driveshafts and a speedo cable extension for speedometer to work. You'll most likely need to modify your motor and t-case mounts or purchase ones already beefed up. Just depends on depth of your pockets. You can use either a topshift or forward shift for crawlbox. Mine was set up as a forwardshift when I needed a topshift. I removed the pin out of the shift rod at the fork. Slid rod forward and cut off excess. Have not had a problem out of it for 6-7 yrs. Rear box has to be topshift and I have no experience on converting it to topshift but sure it can be done.

Check out marlin, Trailgear, and advance adaptors site. I know marlin and trailgear have a step by step instruction guide that should give a good basis for procedure.

As for whose kit or assembled box is better. I personally liked the marlin and went with theirs, it was second hand.

 

Yes i was planning on the speedo extension and new driveshafts. Also the crossmember too. New mounts can be done, theyre all crap now anyways. So ill try and find a used top shift case, ill just use one i find instead of a marlin or inchworm, too spendy for me lol. But as long as a second used case can work ill be set. Ill just run 2.28s for now to save money. Thanks for your help!

 

Just to clarify, you still need and adaptor kit. Used to be marlin a different gear cut on the stubby shaft for crawl box (don't know it's name) the the other brands that kept it engage where TG was dependent on detent ball and spring. So some had problems with the TG set up popping out of engagement. Haven't researched it lately to know if same is true. So research before you shell out cash. Popping out of gear on a steep climb would really be unnerving in my book. But I found my crawl box on craiglist, guy won't seperate it from the rear t-case. Bearings felt good and it cost less than new with a spare t-case.

 

Heres trail gears instructions,

https://www.trail-gear.com/TG/prodIn...0001-1-INS.pdf

I just did a top shift conversion on a case. It wasnt that hard if you can stay organized. Again, TG has great instructions.

Check this link from Marlins T case bible. https://www.marlincrawler.com/tech/t...fer-case-bible

Other good info from marlin. https://www.marlincrawler.com/tech