Several years ago I posted about how I was kind of disappointed in my Jag-stang. The output seemed kind of weak, the intonation wasn't great and the wolf tones on the low E string around the 12th fret were horrible. I recently decided to just see what I could do with it. I was nervous to mod it, since I really wanted to keep all the original parts. So, I decided to just do a full swap of the electronics, pickguard included. While it still has some issues that I haven't been able to figure out, swapping out the pickups was by far the best decision I've made in terms of upgrading. The intonation is still a bit rough, but seems better with the right gauge strings. I've tried different strings, but I mostly used to play with the Slinky Hybrid strings and they just don't seem right for this guitar. Now I'm just using a standard set of 10's and it feels much better. I considered a new bridge, but for right now I'm pretty happy with it, so I'll save that for later (if needed).
For the pickups I decided on a Seymour Duncan JB SH-4 for the bridge position and a custom shop Seymour Duncan Pearly Gates (strat sized) for the neck.
I went with a tortoise shell pickguard that came with copper shielding. I then shielded the entire cavity with copper tape. I got new 3-way slide switches, new output jack (pure tone multi-contact to keep a tight fit), new push-pull pots and added a metric toggle switch for pickup selection. To add the pickup selector switch, I got a custom control plate with 4 holes; one for the toggle, two for the pots and the last for the output jack.
The Mustang/Jag-Stang pickup selection method never seemed ideal to me, so that's one of the reasons I added the toggle switch. The bigger reason, though, is that I wanted to use the 3-way slider switches for series/parallel/coil split control for both bridge and neck pickups.
The push-pull pots add even more versatility with a phase flip for the neck pickup by pulling the volume pot and a master parallel/series control by pulling the tone pot.
This gives a crazy number of combinations for a wide range of tones. All in all, I believe it's something like 42 options. The bridge pickup is great for heavy stuff in the series humbucker mode. The neck Is a bit boomy and dark in series humbucker mode, so I usually either run it in parallel or split. But my favorite sounds involve both pickups being on in different configurations (coil split/parallel, etc). The master series switch is really only useful in a few cases, in my opinion, like with both pickups in coil split mode. The phase flip offers some really interesting tones, too, and it can really vary based on the selected mode of the pickups.
The main thing I think I would have done differently if I were to redo this project would be 500K pots, since I just went with 250K ones without really thinking about it. I feel like some combos are a bit too dark and having 500K pots would give more room for that top end to shine. You can always roll it off with the tone knob, but you can't add it in. 😕
All in all, the build took a little time, because I wanted to tread carefully and make sure the wiring was all going to work properly. I had to sort of piece together bits of schematics from different sites. I also found it a bit difficult to manage the wiring since the Jag-Stang body cavity is so limited on space. I initially wanted to turn the bridge pickup to have it parallel with the strings, rather than angled. But I really didn't want to dig into the body of the guitar. As it is, I have all the original electronics mostly still together on the original pickguard and control plate. I'm pretty happy that the look of the guitar isn't too radically different from the original and I didn't have to modify any original parts.
If anyone is interested in the schematics, I could probably draw that up. I never put together a full document, as I just worked in pieces, hand-drawing the wiring for sections. Let me know what you think!
 
Before                                                                                                                                                 After
 
                         
These images were taken many years apart with drastically different lighting. I tried to color correct a bit without going too crazy. I think the "after" image is closer to the true color, but it definitely looks different depending on the light. The warmer the light, the more it brings out the greenish tint in the paint.
 
Here are some images before the rewiring process:
 


 
And here are some during the rewiring process:

For those who want a custom build. For those who can't find a Jagstang. Why customize an original? Build one. If you lack luthier skills, I can help you.

Does anyone know the original part number for the original hard case that came with a Jagstang in 95? I bought one from Guitar Center that is Fender model 540006004000000 and it says it fits a Mustang/jagstang/cyclone. It is too short and does not have the place for putting accessories in.

Okay, this may sound a little weird. But I can just easily lift the knobs off the guitar. It was already this way when I got it and never took action to fix it.
I have no idea how it got this way. It's like they were never actually tightened. My question is, what's the best way to get them tight/locked in place?
So I can turn the knobs without worrying that they'll come off.