You can buy resin cowl hoods & shorty Sweptline beds for cheap but they want $125 for a cab & interior tub another $15-20 for a Lil Red kit for the rest

If you dually one the tires & wheels are $40
The Ford kit to dually the right way is $35-50

I used a GMC wrecker kit for this Lil Red Cab forward chassis & all wrecker chassis in the rear

Dually kit for $23 shipped