I am converted jeep guy and now thinking about trading one of my tundra's for 86 4runner. Looks pretty good but guy says 4th gear is out. Runs fine all other gears. Is this common? 4th seems like strange gear to tank. Called local transmission shop and they said internal parts been hard to come by lately. Y'all having any issues with parts? Should I try to find used transmission (w56 I think), order rebuilt? If so from where? Or just have locals tear into it. I've always been scared to dive into a transmission.

 

Now’s a good time to learn! Yes, 4rth would be strange, maybe it’s popping out of 4rth? I believe that might suggest synchros. I have seen that on a high miles Toyota 5 speed that was not abused.

Lots of videos on YouTube about rebuilding these and parts kits available. But also used ones available on market place and Craigslist.

should be a w-56B. Check out the identification page here https://www.marlincrawler.com/transmission

 

It's not a bad transmission to work on. A FSM would be pretty essential.
Besides standard tools you'll need a gear puller set combined with a bit on ingenuity, and access to a press.
Gaskets, seals, bearings, synchro's, etc. are easy to come by. Shafts and gears are getting tougher.

4Th is an odd one to lose. The most classic trans issue on the W56 is noise from all gears BUT 4th.
A better description of what 4th is actually doing would be good. "Grinding going in", "popping out of 4th", etc.

Price a rebuilt from a decent company. That way you know your worst case. Marlin Crawler is one good option. They rebuild using quality bearings.
Then take yours apart and see if it's worth giving a shot. Take a ton of photos as you disassemble. I like to lay things out on cardboard in the order I take a part. Magnets and cups are great for detent balls, springs, etc.

 

Seller told me he thought synchronizer out but couldn't use 4th at all. So not sure what it is doing exactly, but I'm gonna check it out this weekend. Looked at marlin but any ideas how much it would cost to ship my core to them from Arkansas? May not be worth the core charge.

 

I'd probably look at UPS ground. You could guess the weight at 75-100lbs and get an idea.
If the shipping cost wipes out a big chunk of the core money you could always part out the trans and sell the shafts and gears on eBay.

 

Ok, finally got to take it for a spin. Shifted into 4th and did fine. Went to fifth and everything great. Back to 4th, coming up on end of dirt road and slowed down for stop sign and got stuck in 4th. Had to hike back home and get tundra. Wife pulled me until fast enough to get out of 4th. Then limped home using 1st-3rd. Syncros? Could it possibly be anything else?

 

I'd say the first step would be to drain the fluid into a very clean container and see what you get. Metal "grit' is one thing, but pieces is a problem.
If they gearshift lever feels sloppy you could always pull the shifter out and check the bushing on the bottom, but I'm not terribly optimistic it'll be that simple.
If the trans does come out I'd look at the input shaft, sychros, hub/slider/fork, etc. If the previous owner had used the shift knob as an armrest I've seen that cause odd wear on the fork and slider.