These photos are of a Diablo of unknown origin. We wondered if this is a prototype of some sort.

Note the handle bars are from a 503 and the bogie rail does not have the mounts for the bogie assemblies. Also, the cleats are different. 

If anyone has information on the origin of the above, please email us.

Terry writes:

Thanks for taking the time to put your site up on the net.I think its great! My name 

is Terry. As I was looking through your site, I came across the prototype 
page and thought I would respond to the question of what the unit pictured was 
from my experience in the past. 
 
I grew up in Colorado and as a youngster we had a Diablo back in 1968 and lost 
it in a fire in 73. We had a lot of fun on that machine and also did a lot of duties

around the ranch when the snow got deep. 

As I recall some time in the early 1970's, an aftermarket company (don't recall 
the name) came out with a retrofit system to replace the bogie set up with the 
teflon slide rail system seen on the one you have pictured. Because there were 
quite a few problems with the bogie wheels getting bent or seizing up from 
ice, or distortion when traversing rough terrain, impacting rocks or 
stumps, downfall trees and other objects. If I recall correctly the dealer out 
here sold those retrofits for close to $100,00. 
 
The track cleats that are pictured were available for the purpose of improved 
traction in deep powder snows and worked very well in the mountains were the 
powder snow gets pretty deep and everywhere you go is up or down on quite steep 
inclines. The adding of a deeper cleat following two or three shallow ones 
also had a relationship to gear ratio and available horsepower to pull them. At 
this altitude, two many deep cleats had a noticeable effect on performance as 
well as how long the rubber drive sprockets would last. 
 
I'm not sure that this is the what you have on the unit pictured but it sure 
looks identicle to the retrofit that was available at that time. 

Ken P writes: 

Looks like someone tried to upgrade to a slide-rail type suspension. The old Cat 

suspensions, best of my recollection, were steel and had those big stirrups on top 

at the leading edge. Based on what I saw, that immediately came to mind. With 
respect to the belting and cleats, I don't have a clue. 

Mike N writes:

That prototype chassis is neat! 
 
I would surmise to say it was a 1970 Diablo "504" with slide-rail suspension since all the majors were going to that 
type of suspension design at that year. The manufacturers found that they could increase profits, simplify design, 
reduce weight and complexity, and deliver a better ride all by adhering to that design.
To be able to find an intact chassis of that design is fantastic!
 
 
Ron O writes:
 
Looks to me like someone retrofitted a 500. The muffler is located underneath. Doubt to be a prototype as it looks to be 
like someone decided to put slides on a 500. Look at the underside of the track up top. The sliders are eating away 
at the track. Any prototype of that year would have had metal track clips for the sliders to ride on. This one just has 
sliders riding directly on the rubber track chewing it away. Look how rusted the slide is in comparison to the still 
black paint of the frame. Looks like it was heated or welded. We have been thinking of putting slides on a 500 we have. 
The biggest issue is contact between the slides and the track. We would have to make a 4 piece track. The slides 
would need to run behind the sprockets like a Hus-Ski.

Barrie G (the owner) writes on 4/1/08

Very interesting comments on the Diablo prototype. That track info was 
surprising. I agree with the guy who said it is a model 504. Here is what 
they don't know...this machine is 8" shorter, 2" narrower, 4" lower and each 
track is only 9-1/2" wide. This is not a modified 500 because everything is 

smaller than a regular Diablo but I believe it to be authentic Diablo because 

all parts are a study of 500-502 and 503 models. 

Roy T writes us on 4/7/08:

Mike N writes on 4/4/08