If a doubler costs 1/3 again that of an adapter then I'd rather have the lower gearing option. In other applications doublers are in this price range. Do not yet know about 60's./quote]
Sounds like you will be replacing most of the drive train. So the Marks is not for you.
I've pondered this. My Sub is currently 3.73 with 285's. To put the engine in it's ideal rpm range in OD the speed is a bit high for that size vehicle. I've gone back and forth over this with that vehicle. The final say will be towing the Baja. At that point if the high passes shut me down too much, then I'll reconsider the gearing. I have the tools to do my own gear set-ups, so it's not like I have to take it to a shop.
33-10.5's or 255/85's are the total range of tire size choices I'm considering. I have the former in both A/T and M/T already on 6 lug wheels.
The sweet spot on a 60 (stock) is about 2000 to 2500. At low speeds you are in the strong torque zone. Highway speeds and towing is where you'll feel the difference. I settled on 31 X 10.50 MTRs as ideal for the 3.73 gears. In 33's I would go 10.50 or even 9.50 -- pizza cutters :sombrero:
A front ARB would be more as insurance than for regular use.
At first it will get an OME. Should I stay interested and motivated in the vehicle it will get a radius arm - coil spring front conversion. I've BT,DT with making front leaves ride nice (approaching that of a coil sprung rig) and don't really care to repeat that whole ordeal.