Transmisson noise

I have 3 mazda pick ups, one long bed, and one extra cab, and one standard cab. AND my dad has a extra cab (or cab plus whatever you want to call it). ALL of them exept for one, the transmission is pretty darn noisey. on two of them its really bad. 1,2,3,and 5 all make noise going down the road but 4th is smooth and quiet. any body know why this is? one of the trucks is worse and has 250,000 miles on the tranny but the other one only has 170,000 and is little better but is still very noisey. Does anybody know what this is? what bearings i guess i could rip one of them apart and see what i find soon when i replace the tranny in one of them. but any info would be bitchin thanks.

Chances are one of the counter shaft bearings is going/gone bad. If you replace it soon enough, you'll save the gears. If not, irreparable damage is imminent!
1,2,3, and 5 all use the counter shaft. 4th is a 1 to 1 gear, so no mechanical change between engine rpm and drive shaft rpm.

These transmissions use sealed bearings in them. Why I am not sure, there is no dirt in there, and there is oil everywhere.

You guys ever seen a factory sunroof in these trucks before? Haha They seal horribley, after 27 years or so.