I'll also post some ebay sellers who ocasionally sell 70 mopar seatbelts.
I agree, it was one of the hardest things to find the correct style for 1970.
It took me more than 6 months. I also finally found them on ebay.
Then you never find a FULL set.
If your lucky and no one else sees them you may get them for $100-200.
If there are alot of bidders--Well, I've seen them go for more than $500
http://motors.search.ebay.com/_W0QQfgtp ... FSQ3aMESOI
http://motors.search.ebay.com/_W0QQfgtp ... FSQ3aMESOI
http://motors.search.ebay.com/_W0QQfgtp ... FSQ3aMESOI
Talk to people at your local cruises too. You'll be suprised what you'll find right in you own town.
I needed shoulder strap clips and found a guy locally who had Cuda rust buckets waiting to be restored--and there they were.
Just save these links somewhere and just keep checking from time to time.
Then to add to all that and you DO find some and they need restoring--Well
you can do it yourself(don't recommend), They may need restraping and rechroming -or not. Depends if you want to rely on 35 year old stitching or not.If you send them out= big bucks, sometimes more than you paid for them.
Seatbelts are a hard find. Good Luck.