Oilhead TDC Locating Mandrel
The BMW OEM TDC Locating Mandrel (R11S, RT and GS) at the time of this writing cost $32.68 USD.
A substitute can easily be fabricated for approximately $3.00 USD with a Square-U bolt available from almost any hardware store. The bolt used in this document came from Ace Hardware and cost $2.49 USD. The shank of the bolt that was used measured 0.326” (8.28mm). Check the diameter of the shank as they do vary slightly.