URS6 mystery holes in frame rail?

[Ilkorin]

I've been going over the URS6 underbody doing rust repair / paint and came across two pretty big factory holes in the frame rails just in front of the rear crossmember holding the diff. These exist on both sides of the car, and in both cases were taped off with fabric tape to keep water / grime out of them. I'm pretty sure the tape is not from factory, but does anyone know what these holes exist for? And where to find rubber bungs for them because I've trawled through ETKA and can't find any reference to them.

I'm 90% sure I'll probably end up sticking tape back over them, but I thought I'd ask because if there's a proper way I'd rather do that....

[Monkeymagic]

Most VaG cars have this and will be taped and sealed over. I assume they are for jigging on tracks.

[Ilkorin]

Learn something new every day! Was not expecting tape to be a factory solution - I'll tape it back up then, thanks!