I've searched the other threads and didn't really find a complete answer to my question.
I started this project in the summer and haven't really touched it since, but here it goes...

Problem: I have an old '91 Merlin frame with a ghetto Grease Guard BB.

Question: Can I toss the old Grease Guard and use Phil Wood PWX03 bearings and a new spindle without the Grease Guard system?

Thanks for the help.

Grease guard BB are designed to fit into standard BB shells so
any BB designed for the formerly standard BB shell should fit.
(nominal 1.37" ID by 68 to 73mm wide).

A merlin with a ghetto BB? Weird. Why not change out everything?

Some pics if this helps at all.

..pics didn't post.

You need to link them from an outside source such as Photobucket. Google it. It's free of charge. You just transfer your photos from your computer to Photobucket (or whatever you decide to use). Then insert the link Photobucket gives to your pictures.

https://www.flickr.com/photos/34800566@N08/3225629745/

https://www.flickr.com/photos/3480056...n/photostream/

...You'll have to excuse the cat hair.

should work. threading should be standard like sch said.

Here is is cleaned up a little bit- How would I go about removing it?

https://www.flickr.com/photos/34800566@N08/3227546602/

https://www.flickr.com/photos/3480056...n/photostream/

Thanks

That's the one they made with precision bearings held in with circlips.
Just read the code off of the side of the cartridges and ask your dealer to order new bearings.
Pull the clips out with a pair of retaining ring pliers, and carefully tap the spindle with a rubber mallet to press out the bearings.

Here ya go...
6903 apparently, but off the top of my head that doesn't sound right, so read the #'s to be sure.
https://www.bikeforums.net/archive/in.../t-345381.html

Your pix help, and by removing the spring clip readily visible, the BB should just
extrude out to one side or the other with a modest push on the axle. The
bearings would be best pushed out by a cylinder just enough smaller than the
ID of the BB shell but it should not be hard to extrude them. Once out you
can pop the bearing off the axle and measure the thickness, ID and OD of the
bearing and compare with the PWX03. You can replace bearing, or bearing
plus axle as desired. BB shell on your Merlin not likely to be threaded so
using fluted oversized axles would require some machine shop work some where
(threading your shell if it is 36mm ID, or something more elaborate, I suspect
Campy Ultra torque could be adapted for example)
Subbing a Phil axle would require some certainty that the bearing stops on the
Phil axle are very close to where the bearing stops are on the current axle.

My original research on Grease guard only popped up the version suitable for
standard BB.

The Phil website says they are compatible, so I'll check it out.

Thanks for the help.