Got an alternator from a 1996 rangie with gems engine, shop confirmed its 120 amp, do I need to change the pulley or anything or is this direct drop in bolt up on my 1998 d1?

 

The pulley is a bit smaller in diameter. What that means is it will charge at a higher amperage at a slightly lower engine rpm.
Been running one on my '95 like that for years.

 

Cool that's what I wanted for the winch, not bad for iirc $20

Alt shop ran on bench for a while said works great

 

pulley is the same on 4.0. only the 3.9 serpentine used a different size

 

All done works great, will this throw off my tach?

 

You should be able to check with that scanner you've got. The RPM signal from the live data will be from the crank sensor while the tach is from the alternator.

 

If the pulley is the same size it won't. On my '95 it did a bit, but I didn't really care.

 

Well the ug and teach are close enough, pulley looks same without measuring it

 

Does the '95 not get it's signal from the coil? Or does that only go to the ECM?

 

Read the 95 ETM on "Starting and Charging". "Voltage pulses are taken from the engine Generator (Z106) and are generated when the engine drive belt turns the Generator pulley. The Tachometer responds to the frequency of the voltage pulses......".