Hi guys,

New to the forum. I have a '99 Suburban 6.5 and a '95 2-Door Tahoe 6.5. How do I tell whether I have an "F" engine? I can't find anything in the FAQs.

Sincerely,

Rob :)

8th digit in the VIN #

F = Fast (non EGR)
S = Soot (EGR, the ugly rusty thing on the upper intake)

Here's some info from the too much time on my hands file.

All Tahoe/Blazer/Yukon w/6.5 are 2 door 4WD, 1/2 ton, 6 lug wheels with "S" engines.

All 1/2 ton Suburbans w/6.5 are 2WD 5 lug wheels with "S" engine.

All 3/4 ton Suburbans w/6.5, WITH 8 lug wheels 2WD and 4WD, have the "F" engine.

There are some mis-badged 1/2 ton Suburban's out there, which are actually 3/4 ton's, on which the "VIN" even identifies it as a 1/2 ton, but this confusion is easily cleared up as soon as you try to install 1/2 ton parts on it.

There is an additional oddball out there called the light duty 3/4 ton suburban which has 6 lug rims on both the 2WD and 4WD and has the "S" motor.

If your Suburban has 8 lugs it is a 3/4 ton. "F"
If it has 5 lugs it is a 1/2 ton. "S"
If it has 6 lugs it is a LD 3/4 ton. "S"

Physical differences between "S" and "F". Pull the TURBO POWER cover off your engine "S" engines have an EGR valve on top of the intake manifold, and "F" engines do not.

Further, the F with a reflash or boost fooler can ditch the vac pump and solenoid for an adjustable spring loaded wastegate.

The S engine's have 3x the solenoids and are looking for vac on the firewall mounted barometer to make boost and keep the ECM happy. Too convaluted for me.

Just open the hood, look on the driverside of the Turbo Power cover near the firewall, 1 solenoid means 'F' engine, 3 solenoids is an 'S'.

MDT you forgot one in your too much time catagory 6 lug K1500 pickup trucks, S engine/VIN, mine isn't that anymore but it started off life that way.

I thought QM told me I had a 5/8 ton?

Quote from QM. "The S engine's have 3x the solenoids and are looking for vac on the firewall mounted barometer to make boost and keep the ECM happy. Too convaluted for me." When I removed the vacumm system off my truck, I had to leave the solenoids and the fire wall baro electrically hooked up or I had a SES light. I just yanked off all the vacuum lines, The computer wants to see the baro and solenoids present but has no feedback loop to let the computer know if they are doing anything.

I thought QM told me I had a 5/8 ton?
Somewhere between 1500 and 2500, not trying to confuse you.

Somewhere between 1500 and 2500, not trying to confuse you.
I knew you were joking QM, I was just trying my humor because Dieselpro said it needed work. I guess I have to keep trying):h

looking thru this thread according to my vin I have an "f" engine ... and I have 8 lugs so I guess its a 3/4 ton ... thx for the info ...

I still don't understand the diif on a "k2500" or "C2500" ...

"C" chassis are two wheel drive, "K" is a four wheel drive.

C = 2x4
K = 4x4

So i guess if you were driving 2 wheel drive dually you'd be driving a 2x6...... lol

So i guess if you were driving 2 wheel drive dually you'd be driving a 2x6...... lol

Actually it would be a 4x6 :D

I never did fully understand the 3X3 concept for the crew cab. Is that 3 guys and three girls?

ty for the answer .. now time to post up 2 new questions for you guys ... Off to create a new post ...