Pretty sure on these(age) they are behind the firewall bit, behind the engine, if you look through the slits in the wiper scuttle you should see it.
That being the case simply pull off the seal from the firewall where it rests against the closed bonnet, then there will be a plastic shield to pop off, careful they can be brittle, to expose underneath the motor, normally held on with just a 13mm nut each end, resistor sits on top of it.
tabetha