653 had the A1 upper with teardrop forward assist and a 14.5 inch light weight barrel. Or should I say MOST 653's. The Israeli’s bought a lot of these little Carbines from Colt. Colt started assembling them with just about every configuration of parts available during the early to late 80's. C7 type uppers, large and small round forward assists ect. No one is making a true A1 upper anymore. You can find them at gun shows and on the here on the EE every now and then. Original 653's, like all M16's, are small hole uppers. Hope this helps.
Here is a break down of the standard 653.
[img]http://www.hunt101.com/img/059660.gif[/img]
Here is a pic of a Ranger with a real 653 cerca 1986.
[img]http://www.hunt101.com/img/054176.jpg[/img]
An IDF troop with a CAR-15 and M203. Note the C7/C8 type upper and teardrop forward assist.
[img]http://www.hunt101.com/img/054165.jpg[/img]
Here is my C8gery. Very similare to the 653 but has the C7/C8 upper (A1 with left hand deflector). This rifle has a Colt 14.5 inch light weight 1/7 twist barrel with a Vortex pinted on the end.
[img]http://www.hunt101.com/img/056405.jpg[/img]