Hilti TE17 Bits

[scratchedup]

I have acquired this old tool. It still performs very well however I would like to upgrade the bits.
Can someone explain which types of bits it buy and which are interchangeable? The Hilti sites list connection end- TE-C (SDS Plus), TE-Y (SDS Max)...

 

[cgrutt]

Cool drill. What's diameter of shank? I'd guess SDS-plus may work but note modern bits have four slots (two large and two small) the bits in picture look like there is only one large slot. Believe SDS Plus diameter is 10mm. SDS Max is 18mm.