These are designed around 12 valve Cummins swaps on 1973-79 Ford pickups. I imagine they will work with similar engines and earlier years. 

The passenger / turbo side is 2.75" diameter. The driver / intake horn side are 3.0" diameter. The one elbow for the passenger side of the intercooler is 2.75 x 3.0". 
 
This does require cutting your core support where the 90 degree hoses come off the intercooler. A 3.75" hole saw works well and is the smallest you can get away with. 
 
The metal pipes are thick wall stainless, and the rubber pieces are high quality silicone. Premium quality hose clamps are included.

Included: 
3.0 x 3.0 elbow
2.75 x 3.0 elbow
3.0 x 3.0 hump straight
2.75 x 2.75 hump straight
2.75" stainless steel tube, offset straight design
3.0" stainless steel tube, 45 bend 
hose clamps for all connections 
drilling template for the hole saw cut through the core support