Time for some compliments and critisicisms... the criticisms are longer, but don't get the wrong idea, it's because "this is awesome" can be said very quickly, while pointing out criticisms takes longer.
Cool things:
1) The model itself! The shape is a fantastic recreation of that small 2D picture.
2) The LEDs! I was wondering how you were going to do the green glowing rectangle, and your three rows of LEDS on the right-hand side of the weapon are really cool! It was also a nice touch that you based the left-hand side on the green bit from Fallout Tactics. Purists that aren't fans of Tactics can't complain, because in Fallout 1 and 2 we couldn't actually see what the left hand side of the weapon looked like. The two flashing LEDs on the left-hand side of the scope are a nice subtle detail.
3) I was wondering how you were going to do the ammo magazine, thinking that it would end up looking different to the original picture due to it using Fallout 3's block of three small energy cells, rather the original picture looked like a solid rectangular ammo magazine. Cleverly you put the small energy cells into an alcove on the left hand side of that magazine-thing, so from the right-hand side it still looked just like the original picture.
Things that are neither good nor bad, just worth mentioning:
1) It's a shame that when you reload the animation looks like you pull a lever/handle that isn't there, but I guess that is unavoidable as you are limited by the original animations. It's no big deal. It's also a shame that there is no energy charge-up sound when you reload, but again, weapon reload soudns are determined by animations rather than the weapons themselves, so while it is easy to replace the firing sound I can't think of an easy way to replace the reload sound, other than creating a whole new animation for just that weapon.
Not so cool things:
1) The original Glock 86 picture in Fallout 1 and 2 looked shiny silver and new and futuristic. (Same for the original Wattz 1000 laser pistol.) Since they were locked up deep underground in military bases, and only recently brought out by the Children of the Cathedral or the Enclave, it made sense that they were in good condition. Your weapon looks black rather than than silver, and looks a bit beaten up. I guess this is in keeping with Bethesda's Fallout 3 designs (the lasers and plasma weapons in Fallout 3 look quite old and beaten up, and the laser weapons are black), and in fact you did a really good job of making the Glock 86 fit in with Bethesda's world. It fits in right alongside the other Fallout 3 energy weapons. But, from a purist perspective, it doesn't match the appearence in Fallout 1 and 2. This is especially important if the player is not using the total replacer version - if the Glock 86 is a rare weapon only found a few locations, it'll be cooler if it is a nice shiny bit of pre-war technology, starkly in contrast to the Enclave's home-made plasma pistols.
I'm may be able to make the Glock 86 look more shiny and new myself with a quick bit of texture editing and making the black parts grey. I'll let you know how I get on, you might perhaps like to offer it as an alternative texture.
2) The original Extended Cap picture didn't have a long glowing green tube, it was just the same brown colour as the bit underneath the barrel and on the back of the gun. (Looks nice though!) If having the tube be completely brown is a bit too boring, you could maybe make it silver instead, or make it have a thin lines of LEDs on it rather than have the entire tube be green. Also, if you really like the glowing green tube you could have it on just on the left-hand side of the pistol since we couldn't see what the left-hand side looked like in the original Fallout 1 and 2 item picture.
3) The original Glock 86 had a purple scope lens rather than an orange one. This is extremely minor, as your orange scope looks great. But a purist might insist that it should be the same colour.
4) Ever since I suggested added green electricity to your P94 plasma rifle you'd made crackling beams of lightning a bit of a trademark. Was great on the plasma rifle and the pulse rifle and the tau rail rifle... in this case I'm so sure it works well. Placing it on the back of the gun, facing the user, seems a bit dangerous! And rather than a professional pre-war Glock sidearm it makes it look a bit like a homemade weapon like Fallout 3's vanilla plasma pistol.
Perhaps if there was transparent glass over the electricity (like the front of the vanilla Fallout 3 plasma rifle), or a transparent mesh (I've done a retexture of the vanilla Fallout 3 plasma pistol that makes the lightning chamber have a transparent mesh, and there's also something similar on the Fat Man). Or perhaps if the electricity was on the left-hand side of the pistol (where you currently have a non-transparent mesh), rather than the back itself... I imagined the back of the pistol being simple smooth metal.
5) The lightning beam on the back of the pistol stays active even when the weapon is hostlered or lying around... pick the gun up wrong and you burn/electrocute yourself! Holster the weapon and a bit of clothing could catch in the lightning chamber and you could set yourself on fire! The lighting on the original Fallout 3 plasma pistol and plasma rifle turns off when the weapon is holstered or lying around unused, it would be cool if you could do that.