Cooling system problem
 

You will soon tell that I know little about cars. My son's 87 Supra turbo has a coolant hose running from the rear of the engine (nearest driver) to a plastic contraption mounted on the firewall. The inlet tube on this plastic piece has broken off. Can someone tell me what this plastic thing is called and is it hard to replace if we can find a replacement part

it's a heater vsv switch

it's a vacuum controlled valve that allows coolant to flow into the cabin and the heater core

http://www.ddmcse.com/turbo/heatervs.htm

Thanks for the info - much appreciated