I have a 67 belevedere11 previous owner replaced k frame to put 383 in car my question is there a way to find out what year the k frame is I'm looking to rebuild front end and need to know year ..also about gas mileage what is appropriate mileage for 383 4bl 4sp with a small rear...(approx).

 

Bushings are standard sizes, so it shouldn't be a problem. Gas mileage depends on the gear ratio ands your right foot

 

Carb jetting and condition will also have an affect on milage. Also Double Pumper Holleys are very thirsty so don't go that route if MPH is important to you.

 

what do you mean by small rear? 2.75?

 

Your car has an 8 3/4 differential. It could have 2.91,3.23, 3.55 unlikely - gear ratio
2.91 will give the best fuel mileage. Look to see if there is a metal tag under one of the bolts the original ratio will be stamped in it..

 

Rear I believe is 2.90 carb is a vacumn secondary holley....I don't even think I'm getting 1 mile a gallon .mechanic just changed sparks plugs and mileage is still poor..this mpg is normal driving...