Quoted: I was just curious what is the difference between PVS7A's, PVS7B's, PVS7C's and PVS7D's? I always see the different models but was never sure the little differences? Thanks

You gonna make me get my history books out are'nt ya!  hehehe

Ok..The PVS-A's and C's are Litton products and the PVS-B's and D's (Delta model) are ITT.  The Litton's C's I think are water proofed to 33' while the ITT B and D are 6' for a half hour.  Parts are also not interchangable between the two company models as well.  I have not seen PVS-7A's or C's around for a long time, probably because Litton does not do much night vision lately.  I might be missing some other little facts on the units, but this in the major stuff.

The Delta units had extra accessories and came with a tube data sheet.  Limited stock B's are out there now with Select A tubes that are better spec'd than the normal ITT issue B units. Some VERY high spec'd at that.