I spent about six hours (manual said 1/2 hour, ha!) but finally installed an aftermarket transmission oil cooler in my '74 164. The problems lay in a lack of holes to insert the new transmission lines (needed to drill holes) and stuck bolts on the transmission/radiator interface. The good news is that the car shifts much better. However the engine temperature seems a lot lower than normal. On this 164e and all my other 240 Volvos, the engine temp stayed right in the middle (ie around the "N" on the temp gauge). After I installed the transmission oil cooler, the temperature remains half-way between the "N" and "C". Is this a problem? I'd hate to install a thermostat, given the tight fit of the hoses and plugs.