Back when I was wrenching the big rigs, some guys would convert Roadrangers to OD by swapping two gears on the countershaft. Don't remember the exact procedure, but it was a pretty common modification for the shops that did their own trans repairs.
Jerry
Edit: I believe I've heard about some aluminum block 4-53's out there, in some sort of military application. Anybody got some definite information on them?
Jerry
Yes. most Roadrangers can me made into an overdrive by simply interchanging two gears, no parts to buy.
In my case the small Roadranger transmissions (610, 6610, 613, and 6613) are not that simple. To do it right they require the purchase of 5 new gears. Although two gears can be turned around for an OD, it messes up the ratios and you effectively have a 9 speed and not a 10 (5th and 6 gear are almost the same).
The aluminum block Detroit's you are talking about are actually 3-53 engines, and they were used in the Gama Goats, the engines are still readily available and cheap, some things about them are quite different from a regular 3-53, and most people change a number of small details before re powering with one., if your were curious, the head is still cast iron.
Detroit also made some aluminum 6V53's and some 4-71's, used primarily for mine sweeping boats, non magnetic. perhaps they mad some other aluminum engines, but I am unaware of any aluminum 4-53's.
Grigg
