I drive about 25 miles each way to work and my transmission is whining like crazy!
Might be the transfer case. Does the whine change much in different gears?
4th is direct drive. The input shaft is locked to the main shaft. There is no power transmitted through the counter shaft. No power is transferred through any of the gears. No side force on any gears and very little thrust load on the bearings. If 4th seems substantially quieter than the other gears, you may have some transmission issues. I have a transmission, that is in need of a definite rebuild. No whine, but lots of other hisses and growls. It sounds more like a kitchen blender, on low speed.
I still am not able to go over 55 in 4th gear. absolutely no power in 5th gear.
What size tires are you running? Run any size much above stock (205/75/15) and yeah, your Sami will be a real dog. I read on your other posts, you run a Weber. Are you running the stock exhaust? If so, have you checked the catalytic converter, for restrictions? What kind of fuel economy are you getting?
Is there a cheat way to check the tranny? or to see if there is anything wring? I checked the fluid and no metal shavings, and it has plenty of fluid.
Did you check the fluid level in the transfer case? All my TCs have a bit of whine. I expect it, from a 28 year old gear box, with 100k plus miles on it.
Run your TC in low range and see what the difference in noise is, compared to high. It wont give you a definite answer, but the load on the transmission will be less, so, transmission noise might be less, for the same road speed. If the whine is far worse, Id be looking at the TC, as your problem.
My 71 FJ40 Land Cruiser doesn't have a radio. The TC whines so loud, I couldn't hear it anyway. Been that way for the 20k miles I've owned it and its still going.
The Samurai transmissions are very easy to rebuild and the kits are inexpensive. The TCs are a little harder to do, since you have to shim the shaft bearings, to get the clearances correct. If you have the Factory Service Manual (free download is out there on the internet), either one is not problem, for people with a bit of mechanical experience.