My priority is to help identify solutions, not to sell a set of my wheels. <------ I know, from what I have read online though tubeless tires/rims are better than tubed versions. But if those 20 inchers will def work than it would be nice to have something almost exact on there to what was on there.

 

A closer look at one of the pictures you posted does indicate that may be a two speed rear end. I believe I see the shift mechanism at the very edge of the picture.
Something else to consider in this equation is gearing of that three speed transmission. If you go too low ratio on the final drive with too large a tire, you may have a lack of gearing to get it in and out of a tight spot. Does a registration slip indicate what that unit weighs?

 

Yes, tubeless wheels are "better" to have serviced, and in the case of 19.5s would use radial tires that to many guys are preferable to bias ply. But, we never know what a guy's willingness is to spend money vs need to safely make do. The 20s without question will work on your axle, and save overall expense. The cheapest front axle fix would be junk yard 16s, but my buddy Mark can match your 17.5" or help with the 19.5" tubeless style. These, however, won't be inexpensive I don't believe. Stu

 

Therre is only a reg sticker on the windshield from 1989. I do not have any of the former papers for it that would have the weight. About the tire size, yeah that is why replacing the 20 inchers that are on there now with those 20 inchers that are non widowmakers would be the best exact replacement. I would not have to worry about the gearing etc.

 

Nice looking old truck, I didn't see where anyone responded to the question about the switch on the dash, if they did i must have missed it. Its an electronic brake lock. The truck might have lost the factory park brake with the rear axle swap and the electric one was installed to take its place. You should be able to find it plumbed into the brake line somewhere. I am also the guy with the set of 17.5s and set of 19.5s Stu was talking about. I will not split the 19.5 set but if you would want 2 of the 17.5s to match your spare send me a pm. I would agree with Stu that if your on a budget or don't care about factory hub caps, get a pair of junkyard 16s. If your plan is to run factory caps or just want something different than the 17.5s are the way to go. If you decide to go away from the 17.5s I would be interested in your spare.

 

The brake lock you have on your dash in the picture was added to the truck post factory. When I was a kid in high school and college I worked for a lumber yard. All our big trucks had them. The brake line is routed to the dash to that lever lock. It will lock your brakes when sitting and idling. It is much better than an emergency brake, both the kind that uses the tranny or the kind that uses the drums. It was very useful on our lumber trucks that were flatbed dumps or high lift trucks. I wish my 1970 F350 had it.

Google Micro lever lock. They still make them today.

 

thundersnow70 thanks for the reply on the Mico brake. Also yes, I would like the (2) 17.5s that way I have a spare on the front that matches the rims on the front. I shot you a pm. abe that gets me pondering that I will have to figure out what exact model that Mico lock is in case I need parts for it at some point.

I am set to buy the 20" for the rear, so I would have 20" non widowmakers on the rear to replace the 20" widowmarkers and 17.5's on the front to replace the 17" widowmakers

 

 

These Big Trucks are Awesome, I love them

 

That sure looks like a two speed axle from a larger truck. Interesting. Most of those were geared for slow and slower.

 

And that appears to be serious rust on the brake line that runs over the punkin. As Fred said, slow and slower.

 

From the pictures in the Chassis Catalog the axle looks like an Eaton, obviously two speed. The book shows there will be a housing number and series identification on the rear of the axle on the passenger side tube near the differential cover. The Chassis Catalog contains a chart allowing us to look up the axle to identify weight rating, gear ratios, etc. Stu

 

truckdog62563 you mean this one? I looked the other day and didn't see anything on it. I will go out and look again today. Also can you message your friend with the 17.5s. I left a message on here for him and pm'd him but have not heard back.
http://www2.dana.com/pdf/AXSM-0040.pdf

 

Your link is for Dana axles, but from your pics I think you have an Eaton matching this page from the 1964 copy of the Chassis Catalog. If you can find coding on the housing or axle tube we might be able to figure out what you have.

I'll text Mark and have him get with you on the 17.5s. Stu

 

From last weekend:


Doesn't seem to be any markings there but I will check again today.