Jim,I have a "55 2nd with the same exact set-up. In 4th,on the high-side,she'll do 55,but 60's pushing it. I'm also running 9.00 x 20.00's,which are slightly taller than the 8.25 X 20.00's,it origionally came with. I'm thinking of adding a 3-speed "Brownie,when I can afford it. They say that you can achieve about a 12-15% increase in fuel economy,as well as less wear and tear on your drive-train!Just do your homework on the ratios! A lot of useful info.on this site,not to mention so many helpful folks,who've been there,done that. Another option ,(in about the same price range),would be to install a taller gear in your 2-speed. There's a lot of options available. you could even go with a Clark 5-speed,just make sure 5th-gear is O.D.,Not direct-drive,otherwise you're back to square-1. I'm really happy with my 261! I was told to expect no more than 6-M.P.G.,but since I re-built my front brakes,and ADJUSTED the shoes,I'm getting better than 12 M.P.G.-Highway. Before I replaced the brakes,I needed a breaker-bar on a lug-wrench,in order to turn the wheels! the brakes were adjusted-out that far! I wondered why I'd start out in "granny",and by the time I shifted into 2nd,the truck was almost completely stopped!
