For me the amount of space between the strut and drive dog varies. The space is for the cable to have room to wind up some when a load is put on it from the prop. I have more room on my Backlash than I do on my F-41 cat. This is because the cable on the Backlash is over twice as long as the cat uses. So it needs more room to wind up.

Something like these?

Yeah, like that!
I talked to Marc in here a few years back about diagonal slots in the bushings instead of holes for better coverage of the grease on the propshaft. If we want to design a new mousetrap why not go further? I made some up for the heck of it. I didn't have a Vee-block for my drill press at the time either.

Ron,
I don't get it. What do you mean run the stuffing tube as far as you can in the strut. .....and adding more collar to align the bushing in the strut.

The stuffing should run all the to flush with the back of the strut. Then the bushing slides in till the collar hits.
You can stop a tiny bit shy of the end and even let the collar up in the strut a little but the whole bushing is up in the stuffing tube so it would be irrelevant to how much collar you need to align anything. You want the minimum length of collar so the shaft is supported as close to the end of the stuffing tube as possible.

Adding more collar length is just making you add length that the propshaft that is hanging out past the end of the stuffing tube and you will have it wollering around with less support.

Not sure that I'm following all of this
I have a strut like this

That I insert a stuffing tube with a reduced end like one of these

I can only insert the stuffing tube as far as the reduced tube allows anyway? The bushing seems to slot into that reduced section a bit once pressed into the strut.
I figured the perforations where there to create a grease cushion for the propshaft. I never thought that the bushing was meant to spin.
What's the idea of the longer shoulders on the bushings in the other pics posted by HarleyLou?

The 3/8"&1/4" bushing in the Picture was to help understand what you were asking for. Most use 1/8 Strut Bushings Collared or Flared. If your 5/16" stuffing tube won't fit in the Strut, drill it out. Should look like this when done.

Dan, usually I can't get the stuffing tube too far into the strut unless I want to drill it out which I really don't want to do.
I'm just working from my observations in which I don't expect anyone to agree with, just my slant on the subject but it makes sense to me.

One of the things I go a long time ago when I first started in boats was a 5/16" reamer. I run it through all my struts to ensure the brass tube will slide right in. This allows it to go through easily and also lets it move when doing strut adjustments. All my monos get a single wall 5/16" tube and all my cats and hydros get a double wall tube with the 11/32" tube over it. I just leave about 3" sticking out the end to go through the strut and cut it off flush when the setup is complete. Doing it this way ensures the flex cable is fully supported and the bushing is making full contact.
Jimmy

Now I get it. Picture says a thousand words, thanks for that

The bushing wouldn't need to be any different then we always make them if you know how to use them. I can hardly believe you guy's run them like that.
Those setups are crazy if that is what you or Ron are doing for slip in bushings. If you had lead teflons or oilites bushings pressed in the bore of the strut then maybe you would only index the stuffing tube in the front of the strut.

Otherwise,
The strut must be bushed down all the way to the rear. The last thing you want is the collar of the bushing up in the strut running in aluminum. The collar isn't meant to be a bearing running surface. The strut bushing needs to go straight in 5/16" tube and the tube needs to be to the rear of the strut.

The stuffing tube or at least a 5/16" piece of tubing needs to go all the way to the back of the strut. If you can't get it in the slightly snug hole you ream it out. NEVER sand or otherwise take any diameter off the stuffing tube as it will break at the front of the strut.

Get a oversize drill bit or reamer for $10-20 and bore the strut so the stuffing tube goes ALL the way through it, stick the bushing in.

Never imagined it could be so complicated. LOL. I guess we need to have an instruction or an online manual for slip fit bushings.
Just messing with you guys.

Honestly there usually is a few ways to do something but this is one where I can't think of a single other way to properly use a slip in bushing. Other than in a stinger that is already bushed down. But in any case the strut needs to be bushed down and reduced through it's entirety. Even if it is a piece of 5/16" just locktited in but I don't know why just run the stuffing tube all the way through like it is supposed to be.