Guaranteed you can at least tell 92-94 from 96-up because 96-up is the integrated slave cylinder/release bearing design. This has a whole different bellhousing with the square access hole in the side for the slave cylinder bleeder, and hose attachment. If removed from truck already and bellhousing, slave cylinder removed, you can tell the difference because 96-up has the much larger aluminum front bearing retainer with the 2 holes in it for mounting said slave cylinder/release bearing.
Here's some pics.. not sure if I agree with what they're claiming. Worth noting you can 100% ignore the difference in my pics re: tailshaft housings because the 1994 pictured is from a 3500HD so it has the extended tailshaft housing with drum parking brake attachment; the 1996 has the regular C3500 short tailshaft housing with the damper/yoke thingy.
1994 NV4500 from a 3500HD - 6.34 first/reverse
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1996 NV4500 from a C3500 - 5.61 first/reverse
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1994 NV4500 from a 3500HD - note the smaller cast iron front bearing retainer, external slave cylinder design
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1996 NV4500 from a C3500 - note the larger aluminum front bearing retainer, and additional 2 bolts for integrated slave cylinder/release bearing design
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Here's the bellhousing design I mentioned on the 96 with the square access hole for the slave hose/bleeder
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I'm unsure on how 1995 models fit into this but these are very obvious differences between a 1994 and 1996 model. I have a very vague recollection that 1995 is an oddball mix of the aforementioned features but it's gonna take someone with better memory or direct experience to say so.
Hope that helps?
Richard