[roll_the_dice]

Originally Posted by Chuck73080

You have the same rear and trans as the '66 LWB I just bought. Although my knowledge is very limited compared to most of the people here, I have been researching the same subject you have. My truck was originally ordered with split rims as it appears yours may have been. The prior owner changed mine over to 16" tubeless wheels from a later model C30 and mounted 225X75R16 tires which are only 29.3" diameter and would turn the 283 4,126 RPM at 70 MPH.

So, I opted for a Dana with 3.54 gearing, which should drop my RPM at 70 MPH to 2842. Whatever you do I would suggest running tubeless tires as most major tire shops in my experience won't work on split rims from a liability stand point. Granted my experience is based on 46 years driving big trucks, but the 6 years I pulled refrigerated container chassis with split rims between OK and CA was a nightmare of tire problems with split rims. Of course this was with Dayton hubs which are THE WORST to deal with.

Here is a link from Spicer to calculate gear ratio/tire diameter/RPM/speed

https://spicerparts.com/calculators/...alculator#less

I've spent hours with it and frankly it is an indispensable tool IMHO.

Like I said my 225X75R16 tires are only 29.3" diameter, 225X85R16 are 30.4" and 235X85R16 are 31.7". Keep in mind that each time you increase tire size it normally increases load carrying ability, which will increase the price and higher load rating which generally translates to poorer ride quality. You also need to watch the section width of the tire, you never want the sidewalls of your duals to run against each other under load.

Your truck looks great, I'll be watching your progress.

My truck was originally ordered with the big West Coast Mirrors, but the prior owner had them replaced by a single mirror when 4-5-6 Chevy Trucks repainted it in 2015.

My wife thinks my truck is ugly so I'm going to use dual SS 6"X8" mirrors and SS mounting arms from Brother's, a complete chrome grill/headlight bolt in assembly from 4-5-6 Chevy Trucks, a chrome bumper from LMC and SS simulators rather than chrome wheels.

I always wanted a stretched dually chassis with a Hodges bed, and that is why I fell in love with my truck on first sight, although at 10 feet it would have to be a very SHORT car.

Good Luck

Chuck73080
https://www.youtube.com/watch?v=maXSPBlGQl4&t=10s
https://www.flickr.com/photos/184381...57653616824764

Thanks! Great information...I already have the spicer website bookmarked! What engine do you have in yours? Since mine is a GMC, I have the big block V6 305E. My truck is matching numbers and I am the 2nd owner with 60k miles. Only surface rust and is in really great condition. I am keeping the engine and trans...my wife wants me to keep the rear end (money...jeesh), but it is 5.14 I believe...Not sure how to convince her on a new rear end.

Originally Posted by allchevy58

On my 64' C30 I wanted 06' dually wheels so I had adapters made from Motorsport Tech 2" 8X6.5 4.460" to 8X6.5 4.595" tall pilot 14mm1.5 studs for the rear and same without the tall pilot for the front. Put on LT235/85r16 tires, with 514 gears I didn't even try to go on the highway. Bought a HD70 out of a 77' Chevy C30 dually, installed 354 gears and the mileage was terrible and terrible on hills. Changed to 4:10 gears and it is perfect, 3,000 rpm at 70 mph. My truck is pretty heavy being 12' flatbed. The HD70 brought outside of the tires right to edge of the flatbed, looks nice. Bolted right in, had to shorten back half of driveline. I had to have new adapters for the HD70 for hub centric, so if you decide to put 06' dually wheels on the original rear end, I have those adapters available.

That's great information on the Dana 70! I found a Dana 70 with 4.10 gears for $350...but when I asked the guy to measure the width between brake backing plates he said 59 inches which can't be right. He is about 4 hours from me...so I am not sure I want to drive down there to double check him. Do you know what should the measurement be?

Wonder if anyone would be interested in my Eaton HO72 if I swap it out.