[Scrrem]

Your noisy first and reverse gears are very common in the early ZF transmissions. They are referred to as "Black Tag" tramissions, do to the fact that they were manufactured in Germany and the tag on the transmission is black. The gears are cut in a way that makes them very noisy, my 90 was like that, very "Truck Like".

The later ZF's starting in 93 (may have the year wrong) are called "Blue Tags" and are US built and are much quieter due to the fact that ZF changed they way the gears were cut. I changed my to a blue tag last year, and it's much quieter.
Rich