Chrome grills were offered for the 55.. 6v trucks...biggest difference is the hotchkiss rear end...no torque tube...and as pointed out the--option now to go to 3:38 gears. The 55.1 (the last of the breed) was factory superior to the 54 from a highway perspective and incorporated the open rear end which virtually all rodders of prior year AD trucks perform on their trucks to make them hiway capable.
Importantly, the 55.1 was only in production for 1/2 year and in my experience is far more difficult to locate.
