That weight is basic nearly-stripped, meaning not quite what you need to run. Here is the long block weight from my Cummins shop manual, minus flywheel & accessories (starter, alternator, etc.):

CSB (Cummins Svc. Bulletin) 3666087-01
B3.9 and B5.9 Series Engines
Section E- Engine Identification
Specifications Page E-5
General 4B Engine data

4BT= 705 pounds, 320 Kg
4BTA = 725 pounds, 329 Kg

When you get the flywheel, transmission adapter, mounts, accessories (starter, alternator, etc.) and such on there then you're over 900 lbs. and nearer a half-ton.