PART NO.  SPL.PAGE  DESCRIPTION                                                            
6K499     15.F.1    Plug -drain (gearbox)  -Changed to 2K5380 Com.(E)GD101 ( for late 1500
                   high starter type) 
                  The new number is a misprint in the SPL, should be 2K5830
6K499     15.H.1    Plug -oil -drain and filler (2) -(rear axle, 1500)
6K499     16.H.1    Plug -drain -(rear axle, 1600 and 1600-MK-II)
6K499     16.H.1    Plug -filler -(rear axle, 1600 and 1600-MK-II)
6K499     16.H.5    Plug -drain -(rear axle, AWDB model, 1600 and 1600-MK-II) Com.(C)91240
6K499     16.H.5    Plug -filler-(rear axle, AWDB model, 1600 and 1600-MK-II) Com.(C)91240
6K499     TC.A.11   Plug for core hole -screwed (5) -( cyl.head, engine, Twin Cam)
6K499     TC.F.1    Plug -drain) -(gbx.casing, gearbox assy, Twin Cam)
6K499     TC.H.1    Plug -drain) -(rear axle, Twin Cam)
6K499     TC.H.1    Plug -filler) -(rear axle, Twin Cam))

The smaller 6K499 plug has 1/2-14 BSPT thread.
The larger 2K5830 plug has 5/8-14 BSPT thread.

For more information oni this part, see Rear Axle Trch article RA-117.