There is also an independent ancillary take off in the same area as the oil pressure sender unit, however as what IMC has said, swopping out the sender for the independent gauge is my preferred option.
Indeed, I have a tracker on my R35 GT-R which cost £1000.00 initially, and £215.00 annually for the Tracker subscription.
Gives me peace of mind and a discount on my insurance, with a premium of £455.00 annually.
That is the tensioner adjusting bolt that you have snapped and usually only happens if you forgot to loosen off the nut in the centre of the pulley.
Plenty in stock, just drop me a PM if I can help further.
Alex.