Mark X (latin for 10, but always "X" in print I have seen)... were made in Yugoslavia by their state industries. Started back before WW II and made rifles for the NAZIS of WW II. Then did a sporter version. Herter's imported them as XK something, then later the J9. De Haas seemed to think the Herter guns were built on factory 2nd actions... (U9's were BSA --Birmingham Small Arms, England). And a reduced version "mini Mark X" for .223 family. I think Remington is now handling them--both. It is a basic commercial copy (no thumb slot) of the 98 Mauser made after WW II and and drilled and tapped for scope and pretty good shooting iron. Never heard of one with target accuracy, but for a "hunting rifle," no problems. Whitworth was a "version" /model by Interarms. Plainer wood? Different wood. I didn't pay that close attention.
So if you want to clean up and rebuild, for value, look at used values of the Mark X, Interarms; J9 Herters; or the current Remington import. Most parts should interchange. Most stocks for the WW II on 98 Mauser should be "fittable." I would guess you have a "sporter" barrel channel. Metal work, obvious. Any metal smith. Scope mounts, since Interarms is out of business, any factory should have something that fits, but not necessarily stocked by Midway, et al. luck, enjoy...
