Colt 1911 Question

Hi Guys.. new guy on the block here (Ben)hoping you can help me out. I have a Colt 1911 Ser#146796 frame that I believe was manf. in 1917. Left side of frame marked United States Property, Gilbert H Stewart stamp above mag release... Right side has
No(small o w/ underscore)146796 and the top of frame has an H, 8 and G stamped on it. The grips are the newer plastic type, not original as the old ones sort of gave out while the gun was doing a tour in Nam.
The barrel is a High Standard I think, it has an H & S on one lug and a P on the other..
Now here is where I really run into problems... the slide doesn't want to show up in any references I can find. It has no stamped markings on it anywhere,and the left side has Government (over)Model,COLT, Automatic (over) Caliber .45 and then the stallion before the slide serrations. On the right side from the serrations forward, Colt's MFG. CO. HARTFORD CT. U.S.A.
The closest I've come to this configuration is a written description of a rebuild from RIA but I can't find an arsenal stamp on the thing.
I guess what I'm asking is well, anything but mostly does anyone have an idea of the age of the slide and do you think maybe this piece is one of those lunch box jobs or something else?
My camera just bummed out but I managed to get one shot before it did so I will try to send it along. Thanks

hi bshriber,
What you have is an original 1911 that has had the slide replaced with possibly an early A1. The absence of a colt logo on the rear of the slide indicates it's not the original slide and the absence of the cresent cutouts behind the trigger shows it's an original lower. you've probly already checked out this site but if not check it out. during ww2 many company's produced the 1911a1 for the military and my guess is that the slide was replaced with one of those. with the demand for the auto being so great in ww1 the goverment started producing them at the springfield armory. remington rand also made some which had no markings on the right side of the slide. hope this helps JMHO
Kim
http://www.m1911.org/history.htm

Thanks Kim.. That was another interesting site, amazing how much there is to learn from all the sites and all you folks out there even though this slide is still a bit of a mystery. I've had this piece since 1965 but didn't get the history bug about it until now (perhaps because it was in a closet and I'd forgotten about it) and thought I'd find out as much as possible to pass on (gettin' my sh.. in order so to speak). I do have some pics of it and me "in country" so at least they'll have a bit of modern(?) provenance. Thanks again
Ben