Not to my knowledge, even on the flexible aircraft versions and AFV versions, MG3-A4 and A5 restrictively, there was never a provision for a "chuted" feed supply as this is a particularly hard problem to overcome with the movable (liftable) feed tray of the basic MG42 design. Also remember too, that this is discussing ONLY applications were disintegrating LINKS were used, and the Euro MIL applications still stubbornly clung to NON-disintegrating BELTS in almost all applications, save some specific AFV mountings, almost to this day; So, no links, no way would you consider a chuted-feed delivery and that right there is probably the single biggest reason one was never developed.
The need to lift the feed/de-mount the feed tray largely precludes the ability to form a suitable attachment point for the feed "chuting" in general terms; the one notable exception is, of course, the very similar M-60D variant which uses nothing so much as a slightly modified MG42 feed tray, but there were/are significant operational limitations when the 'D' model was used due to the attached chuted column.
For those reasons, the Euro applications of all MG42/MG3/MG42/59/MG74/KK3 variants stuck to the tried and true side mounted bulk-feed boxes, probably a better application.....US doctrinal experience with chuted feeds was long and not always successful, guns that allowed fixed receiver side mountings for the gun-side attachment points for the chute ends like the M1919A5, M73/M219, AN-M2/M3 A/C Basic/Flex/Fixed, AN-M2/3 20mm, Colt M4/M9/M10 37mm, M-134, etc., all worked quite well due to the fixed, rigid, gun side delivery......the M-60D was an afterthought, at best, and if you have ever done an immediate action clearing on the 'D' you will find it a long and tedious process as you need to finger push the belt end back and through the chuted guides as you clear the feedway. It's a mess.....and that's using disintegrating LINKS where all you have to deal with is the belt end and sweeping clear a few spent free links.....would be a god-awful mess with non-disintegrating BELTS that must stay in-line to be sure!!
Still, for the hobbyist-shooter, one could emulate the M-60D application and put together a similar set-up if you really wanted to, but you better limit your thinking to then using M13 links in 7.62mm only!! ;-)
And, No, 8mm will in no shape or fashion feed through 7,62mm NATO chuting, but WILL feed through .30cal chuting though probably NOT reliably as there needs to be full support at both ends as the ammunition column moves through and the 6mm shortness of the 8mm rounds will very likely promote tipping and jamming......YMMV, try it. There is NO GROUND USE "8mm"(7.92x57mm IS) chuting ever made originally, save for the very exotic chutes made for such applications as the MG-81/81Z, MG-17, and similar.
-TomH

Vieles ist bekannt, dass ist nicht offenbart.