George / Duane,

Thanks for your info. I'll try to be as clear as possible.

Its an M-41 with the J-type OD, which came out of a 72 144. Before bolting it up, we replaced all the seals and gaskets that was supplied with the kit which I got from Duane sometime back. Also cleaned out all the oil passages and solenoid. As I drive the car more, we can probably rule out any problems with the O/D. I kept a close look at the tach, and it did not fluctuate in unison with the vibrations. Besides, it catches on right away as soon as you hit the switch, with no hesitation whatsoever. The vibrations feel like the normal vibrations you get thru the shifter as you drive, but somewhat amplified, and can be felt on the entire car. Very similar to a bad U-Joint. I probably got a bad new U-joint.

We opened up the top cover of the tranny. The gears looked great, and therefore we left it as it is. I guess looks can be deceiving. Probably a bad bearing or two in there, or a worn out shaft.

As for the humming sound, very slight in 1st, at above 3000 rpms, very noticable in second between 1500 and 3000 rpms, unbearable in 3rd at all rpms, and no sound in 4th (and in O/D). Bad layshaft? The hum can only be heard when you are on the gas, and it gets louder the more you get on the gas. No sound when coasting in either one of the gears or in O/D. On the bright side, all the gears shift in and out without any grinding, so I guess the synchros are OK.

As a last resort, can the internals of my M-40 (which is in perfect shape), be transfered into the M-41 (except fot the main shaft)?
Now that I have got a taste of the O/D I'd really hate to put the M-40 back in and hear the engine cry when I drive on the interstate. And I hate to do 50 and risk being run over by a semi!

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...and the bricks keep on rolling