Big intake is *only* for GE-powered. Even the newest PW ones with the -229 still have the small intake.
Nearly all GE's got the big intake, only Block 30A through 30D had the small one.
F-16C quick list:
Block 25: PW engine, small intake
Block 30, early: GE engine, small intake
Block 30, mid/late: GE engine, large intake.
Block 40 and 50: GE engine, large intake
Block 32, 42, 52: PW engine, small intake.
Covering all the differences of the F-16C/D family would take a LONG post. But that'll suffice for external parts of the engines/intakes. (Unless we start talking about nozzle feather finish on PW's...)
I don't have a Witty, but Dragon's have the large intake. (Which makes them wrong for Dragon's many PW-engined releases). Dragon's F-16C really is a mish-mash of parts. Not sure about Witty's, the only one I found good pics of was for the T-birds release, and it's painted strangely in parts and isn't a Block 32.
Big intake is the MCID intake (Modular common intake duct), the small one is the NSI intake (forget what it stands for). Personally I'd call them wide and narrow, as that describes it better---the small one is actually deeper than the big one. Best way is to look at the upper corners---the small intake's corners are more circular and broad, the big one has more "rounded off triangles". You can also tell by the ECS intake ducts--the small ones are vertical, from both the front and sides. The big one has them slanted in (from the front) and slanted forward (from the side). From the side, ECS duct angle is the best way to tell IMHO.
Big on the left, small on the right.
