On an 84-88 truck or 4Runner it takes about four hours to change the heater core. Ive replaced the heater cores on two 86 4Runners, the first heater core i did took a little over five hours, but the second one only took about four hours because i knew were everything was and what had to come a part. The complete dash does have to be removed, but its not as hard as it looks, it more time consuming than anything else.

1986 Toyota 4Runner.

Solid Axle Swap, 5'' Lift, 37'' MTR`s, Duel Cases, Detroit Locker Rear, ARB High Pinion Front, 4.88 Gears, Cross Over Steering, Trail Gear Sliders, Addicted Off Road Front Bumper.