Well I’ve been reading that people use a 27mm deep socket to remove the oil pressure sending unit from the oil canister to install an oil pressure sending unit to install an oil pressure gauge. Of course, the socket wouldn’t fit when I tried it on any R53 engines, and I’ve tried many.
After some research, I found a socket from CTA Tools (CTAtools part # 2042) that fits the oil pressure sending unit perfectly. Silly me, I didn’t consider that the R53 engine is a GM/Chrysler motor, and would indeed require a specialty tool that was made for GM/Chrysler engines.
Here is a link where you can buy this socket yourself to install an oil pressure sending unit. http://autopart.com/TOOLS/TOOLSMAIN/tool/T_2042.htm Cost of the socket itself is less than $10, but I could not find it locally and had to pay $10 for shipping.