Re: I need a mercury oil warning module 41470A27 old # 41470A11
For an 88 135, any module from there on up through the EFI series of engines should work. There are several different terminal arrangements, but that's what they make solder and heat shrink for. The EFI versions have an extra wire that goes to the water separator. It's literally T'd into the oil cap sensor wire, so you can just cut it off.
They all have one wire that goes to the ignition for a signal, a supply and signal wire for the motion sensor, a pair of wires for the oil cap, a power supply, a ground, and an output wire. The color coding could vary, but not much.
In other words, any oil alert module on any v6 up to and including an EFI will work if you are handy with tools.
hope it helps
John