can anyone enlighten me about the difference between the two ? and or list their specs.

 

Both can be found in small utilimaster box vans. Both are 4 speeds. The ratios for the 542 are 3.454/2.253/1.407/1.000 and reverse 5.02. The 542 is very similar to the 545 but with a shallower oil pan. The maximum input power to the 542 is 235hp and net input torque at 445lb ft. It is best suited for light- or medium-duty applications of a multi-stop nature such as mini/midi school buses, general P&D, shuttle buses, step vans and motorhomes. It does come with an optional neutral position for a park brake provision.

Here are some more specs:
Length..........................................27 .2 in (692 mm)
Width...........................................19 .8 in (503 mm)
Height............(with standard 3.8" oil pan)..18.9 in (480 mm)
Depth Below Center Line..........................9.7 in (246 mm)
Weight (dry)....................................289 lbs (131 kg)
Weight (dry w/retarder option)..................329 lbs (149 kg)

The 545 has the same max limit of hp and tq as the 542 and the same gearing. The only difference is a deeper standard oil pan at a little over 5 inches.