If your freewheel requires the TL-FW10 tool, it's from the late 70s or early 80s at the latest. While the TL-FW10 may be hard to find, the freewheel uses the same two-slot pattern as Regina, Atom, and other freewheels of that period, so other tools will also work, e.g. Bicycle Research CT-1, Cyclo (English), and VAR 188 (not the Park FR-2, unless you grind the prongs down to fit). Of these, the Shimano TL-FW10 and Bicycle Research CT-1 are the best, as they have a stabilizing ring that helps prevent the tool from slipping out of the slots and damaging the slots. The other tools will work, but you need to take more care to prevent the tool from slipping when applying torque.
Check to be certain that your freewheel requires the two-prong remover; by 1986 Shimano freewheels had standardized on a splined remover that is much more secure than the two prong remover. The splined tool is still widely available from Park Tools (FR-1.3) and others.