I have repeatedly considered dually-ing every one of my 4 S-10s, and actually did some of the mock-up work. But the most I ever towed was an 18-foot utility trailer carrying a friend's '92 Mustang GT, and the stock 4.3 with the stock 7.5" axle did just fine for that, once I re-loaded the car backwards to re-gain some steering control of my S-10 above 60 MPH. That was a RCSB with a custom class 4 hitch.
Your Taco is about as narrow as , and certainly a far weaker frame even when new, than, any S-10, but here are my conclusions:
Axle: should not be from a full-size dually, but should be the 10.5" 14b FF from a SRW 3/4 ton or 1-ton Chev. Millions of these in the salvage yards for under $200. This, with stock steel 16x6" GM dually wheels on 215/65R16 tires would be easier than trying to use the old 'yota baby-dually stuff, especially since those wheels all have egged-out lug holes by now.
Also, the 'yota brakes are no match for my proposal, either.
As for dually fenders, the S-10 had options, as phantom dually fenders were then a popular way of covering Pro-Trac SC 515/45-15 tires on the rear. I was leaning toward the Choo Choo Customs Wildside stepside bed, as much more aerodynamic. I would have had to cut the CCC fenders off their 'glass bed, then 'glass them onto my full-width bed, but their stepside was inspired by, or inspiration for, the sleekness of the '88-up GM full-size Sportside stepside.
I normally build for function, and seldom give the remotest hang about looks, but I sure don't want any rookie cop deciding my rig looks too cobbled-together to be safe. Something like this needs to look factory, and for me it needs to do so without costly custom bodywork that'd be even more costly to re-create if a fender-bender should happen.
