silly Question?

The 18" Enterprise is roughly 1/650 scale. The "real" ship is around 1000' - dividing 1000' by 1.5' = 667 or 1/667. Since the ship is slighly less than 1000' it works out to roughly 1/650.

The 22" Cutaway kit is roughly 1/500 scale. Dividing 1000' by 1.83' = 545 or 1/545. Again, difference comes from using the rough length of 1000'. (Several runs of this kit were shipped in boxes erroneously labelled "1/650 scale, adding to the confusion.)

Aftermarket parts for the 18" kit will either say 1/650 or "fits 18" Enterprise kit" (or words to that affect).

Here are some parts related to the kit (I'm particularly fond of the photoetch set ;) ): http://www.culttvmanshop.com/USS-Enterprise-Classic-18-inch-kit-reissue-from-AMT_p_127.html

Just look for "fits the 18 in Enterprise"

Cult TVman has a bunch of aftermarket stuff and thats how they ID it.

Scale has always been a problem and an ongoing debate among trek nerds {like me}.

It says it's a 650 scale, but it's more like a 532 scale.

There is another kit that says it is  650 is the cutaway Enterprise that measures 22 " while the one you have measures 18".

My best advice is read the description on the part and see if it says "Fits AMT model". Most parts do. Most parts are for that exact scale, not the cutaway so you are pretty safe with almost anything. But for peace of mind, check to make sure is says "Fits AMT model"

MOEBIUS - AMT Model Kit - Star Trek TOS Enterprise Tholian Web - AMT 695

1/650 Scale. The classic Star Trek TV show featured many memorable episodes. This release of the classic AMT Enterprise commemorates the fan favorite episode, "The Tholian Web". The episode featured the Enterprise's sister ship, the U.S.S. Defiant as a mysterious glowing ghost ship. This kit is injected in glow in the dark plastic and includes decals to allow the ship to be decorated as the Defiant or one of several other Constitution class star ships. Also included are NEW parts to create the twin Tholian Web Spinners which were shown entrapping the Enterprise in the episode. Molded in glow in the dark, Commemorating the classic TV episode "The Tholian Web", NEW! Tholian Web Spinners included. Decals feature alternate ship markings, includes cardboard Tholian Web backdrop.

Skill level 2.

Kit is claimed to be 1/650

http://www.cybermodeler.com/hobby/kits/amt/kit_amt_0695.shtml

One way you can check it to measure you model and scale backward with calculating, Most kits released by manufacturers are not really to scale, they are just close to it to sell an item within the scale