Four, the 261 is rebuilt stock except the block was milled .035 and the head milled about .020, #850 head.The B carb is the slightly bigger 261 model, runs a 57 jet. The air cleaner is the typical oil bath model,single exhaust,2-1/2 inch head pipe, turbo muffler and short tail pipe,used to get 18 mpg with the 3.42 gears, now with the OD, around 20 but I drive faster with the OD.The truck has 225/70-15 radials,suspension lowered about an inch. Gears in the 2.70 range do slow down the acceleration some, high gear acceleration in 3 rd direct is snappy,in OD,much less so.The truck always has 3 rd direct to use when the going gets tuff,2500 rpm at 60. With your 1.70 or so second gear,you may be caught between gears when hauling or driving in the hills with a 2.73 gear.But maybe you like the truck tranny and drive accordingly.
And this for us Chevy guys; I used to have a 49 GMC 3/4 ton with a good running 270 and a swapped in 3.73 14 bolt rear end.My brother in law owns the truck now, Joy's 261 truck will easily out accelerate the GMC in high gear. Yeah, I know it's a 3/4 ton against a lighter 1/2 ton, but a win is a win
