I have the same issue but perhaps less pronounced. Backing a straight line in reverse yields little resistance but turn the wheel and it's like stepping hard on the brake. Only in reverse too. I replaced the rear 3rd with a Marlin 4.11 two years back only after being assured it would run just fine with a stock 4.10 in the front. As the 7th owner of this '91 Toy it didn't occur to me that the front 3rd might have been swapped for something other than stock 4.10.
Time to spin the front wheels and discover the truth!
