I plan to install a SEMIFLOATING 14-bolt in my 78 K5. My problem: I have heard that there are 3 different SF-14-bolts (different axle widths for suburbans, trucks and vans). Which one should I look for? What about the spring perches - are they correct or do i have to relocate them for installation in my 78-blazer? I am thinking about wheel spacers for the rear axle due to the different track width (10-bolt front, now 12-bolt rear which is about 3 inches narrower). Could I install a wider SF-14-bolt (e.g. one from a van) and the track width would be similar to the front axle? I would appreciate any help. Please excuse any errors - I am from Austria and my English is less than perfect.