I make drag car gasser axles to any width and install them to suit your car. Sometimes the car can use a straight axle and sometimes it is best to use a 4" dropped hot rod I beam axle. It all depends on the driver position and the ability for the driver to see the christmas tree at the track.
 
I use comonly available 37 to 41 Ford after market hot rod spindles. Spring pads get made to suit the springs, typically widths of 45mm so we can use trailer leaf springs.  The axle ends are tig welded in our own design jigs to hold the king pins square and at the right angle. Same as if it were an I beam axle.
   
As you can see from the pictures these are a well engineered product using good parts to make your dragster as safe as possible with good weight transfer, safe braking and predictable steering and handling for when you are way out of shape.
   
Remember good front end steering and geometry is no accident, so if you don't know what you are doing, just save up to do it properly.  You don't want to be knocked back at scruitineering on race day becasue of a poor job.

There are many dimensional variations to consider that make a one size fits all gasser axle kit problematic at best. I noticed when talking to fellas to try and supply a kit, they just want an axle, they can't answer all the questions but want me to answer the questions over the phone, when I can't see their set up.  Like what width do you need, what weight is on the front of the car, what steering links will fit, it is usually an issue, clearance from springs, clearance to engine and where to place the steering box. Too much to go wrong and hard to mail out, so now I just do a supply and install.
 
On top of that is the sub frame or chassis strong enough, should we strengthen the subframe or cut it out and chassis the car. The steering rods will need to be made to length to fit the position of components and ride height. Also a straight axle may sit the car up too high, it might be better with a 4" drop axle in it? This will largely depend on at what height will the rear end sit at and with what tyre diameter on the rear. A dropped axle changes every dimension so whole different set of parts to a straight axle.

So those looking for a simple kit to suit this car or that, is not that practicle thing for such a low volume item.  I offer to do a complete fabrication and install here at my shop, at an hourly rate. then I sort all of the above out for your model car. Basically I want to avoid being on the phone for hours to people with low skill levels, sorry but I can't afford to do that.
 
Hot Rod spindles and brakes, mounting brakets, springs, bump stops,steering arms, perch bolts, radius rods, etc all the parts can knock a whole in $4,000 to $6,000 using all new parts. I do not stock these hot rod parts any more as there are many importers of varying qulity and price these days, I use the local hot rod retail shops myself and I get them in as I need them. If I am doing the job for you here in my workshop I buy the best parts that I know of and you pay what I pay, I just charge you for the time I take to select and organise the parts I need that will suit the job. If you want to shop around for the parts and supply me thats quite ok.
 
Labour to convert to a straight axle and semi eliptic springs it would be $5.500 to 8,500 or more depending on whats required for your particular model.

If you have set up the springs and prepared the car etc so I can just make the axle and or set up the steering that would be the cheapest for you and the least amount of work for me. I am assuming here you know what you are doing with regards to the other fabrication required and the strength of the car etc.
 
All work is done at our standard hourly rate + parts + materials