I was wondering if the diesel powered F250-F350 trucks (1996) used two battery trays? My truck is a 460 gas but naturally has one battery.When I use the plow the volt gauge shows a major discharge at or near idle.Or is there an alternator upgrade ?

 

3G alternator upgrade. Best upgrade ive done.

Search the forum, there are lots of threads on the upgrade.

 

https://www.ford-trucks.com/forums/9...g-upgrade.html

3G Interchange Facts. If you're thinking 3G read here. - Page 4 - Ford Bronco Forum

 

I just finished the 3G upgrade last week. It is well worth it. I paid 35 bucks at the local wrecking yard for the alternator out of a Taurus. Running a single belt with no slippage or squealing. I highly recommend this upgrade.

 

A 3G conversion would be a really good upgrade, and not that expensive.
To answer your original question though, yes the '96 diesels used two batteries.

Battery tray
RH F4TZ-10732-B
LH F4TZ-10732-D