Depends on the diesel engine your friends trucks have. Some handle ether better than others: and the glow plug or air intake heater systems better be dead or disabled. Otherwise them catching themselves on fire WILL be a viral Youtube video I will find hilarious: because it's only funny till someone gets hurt! Bottom line is only use ether on a 6.2 or 6.5 if the glows are disabled and you don't care if you need to replace it because the
light duty IDI can't handle it very well.
With enough RPM and good hot glow plugs these engines will start. Otherwise something isn't working and needs attention. You need 100 COLD and 150 RPM HOT or FORGET ABOUT STARTING! Gas engines barley move and the spark can fire it and start: not on a diesel.
Have you ever driven a "Can't get out of it's own way" Naturally Aspirated 6.2? Your 350 has more power when it ran. To match the HP of the 350 you need the turbo setup. To prepare for a future turbo setup you need to replace the original 6.2 head gaskets with the modern 6.5 head gaskets and look to short higher pop pressure 6.5 injectors. The old HG's may contain asbestos.
What exactly are you dropping in again? Frankly 6.2 is not telling us the following things YOU need to know:
1) How many miles on injectors as they are toast in 80-100K miles? Cheap, hard to get a good source like
Leroy diesel for them, and use the short 6.5 style with higher pop pressure to clear the future turbo.
2) Block number like 599?
3) Condition: remove the heads and the oil pan. Inspect pistons, inspect mains for cracks, replace rings. Suggest gapless for less blowby and being able to see the marks on the dipstick through the oil at 3000 miles (not normal for these engine w/o gapless rings). Rings are subject to overheating damage loosing their tension and normal wear from all the carbon these dirty engines eat both causing blowby. Deglaze the cylinders and new rings are the only thing required sometimes outside of gaskets.
4) Replace the timing chain. GM allows slop of 0.8" only because it wasn't up to the job of driving the IP and stretches out pretty good even with only 30K miles on them. Timing gear sets are available from Leroy Diesel to cure this deficient GM design.
Cracks are what kill these engines both head cracks and main bearing saddle cracks. Heads are easy. IMO I don't remove the crankshaft when deglazing the cylinders as the stress from the main bearing bolts would change making cracks worse or starting them. It's said
@Will L. any oil pressure concerns look at the cam bearings first. Rod bearing condition will tell you if you need new main bearings.
When in the fuel tank - loose the sock as it's nothing but trouble esp with a pre lift pump filter in use.
Last look at peninsular diesel for a adjustable glow plug controller that is set it and forget it with self regulating plugs like Duraterms or 60G's.
