I had a'75 242 and now I have an '89, although the engines are different they look, and the the procedure is the same. loosen the tensioner, yank the belt enough to get a drill bit in the tensioner hole , make sure your marks on the pulleys are where they belong and slide the new one on. It took me longer than 45 minutes but I 'had to' Armor-All my timing cover, inside and out. wax the harmonic balancer, you know, things like that.

Christopher,

Replacing the timing belt is not a big deal. The belt cost around $15-20 and it takes 30 to 45 minutes to install. On the B21F you'll need to remove the fan shroud and fan-clutch assembly. Then remove the belt cover. Compress the spring on the tensioner with a pliers and insert a drill or nail in the hole in the shaft to keep the spring in the compressed position. At this point you can remove the belt. You need to be careful to keep the belt gears properly aligned when you install the new belt. You might consider replacing the tensioner, about $35, and the crankshaft, intermediate shaft and camshaft seals while you have it disassembled. That will take a little more time. Recommend you get a Haynes or Bentley manual to guide you thru it. Try the local library if you don't want to buy one.

Good luck,

Larry