I've already posted a little about this project on Theopia, and it was suggested to me to go ahead and post the details over here as well. So, here goes...
Back when I was real little, we used to own a Crosman 1389 Backpacker. Of course, being so old, the gun "died" quite some time ago, and recently I wanted to see if I could get another one.
Well, the only ones I could find were "sketchy", at best, and, besides, where's the fun in just buying a stock airgun?

Crosman's air rifles and airguns are all remarkably similar in construction and design. I have figured out that I could make an even better version of the 1389, with parts from Crosman and some modification.
So, here's what a plan to do. The base airgun for my final design is going to be a 1377C air pistol. Here's a picture of it:
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The things I'm going to change are:
1.) Add a 1399 shoulder stock. This is the exact same stock used on the model 1389 and 2289 backpackers, except it will be attached permanently to the pistol instead of having a release lever.
2.) Replace the 10.25" .177" barrel that comes stock with the 1377 with a 24" .177" barrel from a model 1760 airgun. This barrel and the following parts can be ordered through crosman, so it's not like I'll be salvaging parts from perfectly good guns. The 10.25" barrel has a lathed down section towards the crown which fits in the barrel band, so I'll bore out the barrel band that comes with the 1377 to 7/16" to install the longer barrel, being extra careful that the fit is still tight so as not to harm accuracy.
3.) Replace the plastic breech on the stock 1377 with a steel breech, which Crosman actually sells a kit for on their website, (not as replacement parts).
4.) Sand down the brown forearm and paint matte black.
5.) Install a BSA 30mm .22 red dot scope. This scope uses clamps that fit on 3/8" dovetails instead of the larger weaver mounts, so I'm not wasting money buying a 50 dollar 11mm dovetail-to-weaver adapter.
I plan for this to be a neat little plinker. I'll still have the open sights available for use, and the red dot scope will allow "night ops" when I've got a little bit of moon.
There are numerous other modification which I could still do, but I'm going to save until later. I got most of the information to do the above from an airgun forum dedicated specifically to Crosman airguns. The address is http://www.network54.com/Index/12861.
If anybody has any comments contributing to the design of this airgun, please post them here. I have a "MSPaint" visualization underway at the moment, but that will probably take a while.
And, finally, JACK, don't tell me to get a Daystate. I've looked at them... they're decent rifles... I don't want one. Sorry.

EDIT: Check the bottom post for pictures.