Yes, it's normal for the '85 to show lower RPMs than the earlier model years. In 1985 MB changed to a numerically lower final drive. The torque converter was given a higher stall speed so that the same amount of acceleration (term used loosely...) was available.

Don't know that I'd prefer one over the other. The '84 and earlier models turn about 3500RPM if you drive at any decent speed. But it'll last forever being driven like that, so...