Lates start with some basic questions. What year is your truck? Has the motor been replaced and if so what year is the motor? If you have an 81-91 Blazer you will need pedals from a 86-87 Truck or 86-91 Blazer. The Slave needs to be on the drivers side. I have heard of someone using the newer style truck pedals 88-94, but have not actually seen it. The reason I ask about the engine is because if it is an early 2 piece rear main seal then the you may need a special thick flywheel, but if its the newer one piece rear main seal you can get the flywheel from GM with no problem. I purchased all my part from GM, they were expensive, but I have had no problems with them. The 208 should bolt up to the GM tailhousing and work. If you are planning on going to a 205 the tailhousing will need to be changed to a dodge tailhousing and a AA adaptor kit installed to mate them, however if you could find a late model 205 with a round mating pattern it would bolt right up as well.
Layne