I put one on my DD (a Dodge Ram 250 Van) recently. At the same time though, I switched to all sythetic drive line lubrication. Royal Purple engine oil, sythetic trans flush with Valvoline ATF+4, and Castrol sythetic gear lube in the pumpkin. I gained almost 3 MPG. Not sure if the TB spacer or the syns did the trick. Just my 2 cents.
