Crew C30 vs C20 differences

[ElGracho]

Originally Posted by kevinr1970

I am under the understanding that all crew cabs share a "1-ton" frame.
I also understand that a C30 came with a full-float rear while a C20 came with a semi-float rear, but the semi-float is unique to the crew due to the spring perch and shock mount locations?
I am I on the right path here?

So what is different on the front?
Are the Crew C20 and C30 the same upper and lower control arms, or are the lowers different?

I was told that the only difference on the front of a SRW and a DRW was the rotor, but have never confirmed that.

I am going to convert my C30 Dually to single (and short bed eventually) and there is a guy parting a C20 crew.
I have Belltec 3" spindles on my crew now, so I can't just swap all the front end parts over.
Just wondering what all I could grab off this to help me convert to SRW.

True on the same frame.

C20 could be full float or semi float 14 bolt rear. Not sure the GVW that made the change. Not sure if any semi floats made it onto crew cabs.

C20 and C30 without F42 heavy duty suspension shared the same upper and lower control arms. With F42 the C30 is different. See here:

http://www.gmpartswiki.com/query

I would think the dually would be heavy duty (F42) no matter what.

Look for part 14026579 and 14026580 which are the lower control arms for the C20 and the lighter C30 and 14026591 and 14026592 for the heavy lower control arms for the C30 with F42.

The C20 and C30 steering knuckles show different part numbers. All C30s show the same part number so that backs up the rotors being the difference between single and dual wheel front ends. 475083 475084 for C20, 363735 and 363736 for C30.

I pulled these part numbers from my 1985-1991 GM parts catalog. You can look at the same one on the parts wiki.

Originally Posted by andrewmp6

The crew cab was 1 ton only they never made it in a 3/4 ton.As far as a dually to single wheel swap the front you change the rotor and take off the dually spacer thing.The rear you need a whole new rear end and you need a new bed also.The question is do you want to keep it 8lug or are you swapping down to 6 or 5 ?

They did make a 3/4 ton crew cab. Not sure where you are getting this. The 2 wheel drive dually does not use a spacer on the front brake. The brake rotors are one big casting.

http://brochures.slosh.com/1987/gmc5.jpg