I just got a 1969 chevy C/20 long bed but would like to make it a short bed how difficult would that be to do  

Read all about it in Dakota Wentz's "Project Get Shorty" in the pages of Custom Classic Trucks, or Google it, and it should come up on our archives right here on Custom Classic Trucks' website.  

As far as the chassis stuff goes its super easy. one thing to think about though is if you plan on shortening the long bed on your truck or buying an aftermarket short bed kit.  

I actually did this with a 68 several years ago.  I found it easiest to do as a frame-off type thing.  As long as you have the proper tools, some fish plates to use to weld inside the frame and some patience, it is relatively easy.

Make sure that when you cut the frame, you don't cut straight down - you should cut at an angle or a zig-zag.  That will help to strengthen the joint.  Make sure you measure precisely and scribe on the frame before you cut.  Use those scribes as reference points to make sure you get the frame back in tolerance.  If it is more than 1/8" out of square, it won't track properly and you will always hate yourself for cutting the truck up.

I hope this helps.  

That's good advice, thanks '03!  

i think cct did this in an tech awhile back or maybe the other mag did just make sure you have your new bed first as they r pretty hard to find  

You're right we did it here at CCT. Look in the Tech section, We've done about 13 stories so far, and most of 'em are here on CCT's website.