There are some very low clearance garage door openers out there. The iDrive is one of them - my parents use this one on their shop door and it works very well. There is another called the Miracle Opener that requires ZERO clearance, but I have no experience with it. Either would be easier and safer than trying to modify your trusses.

Here is a link that might be useful: iDrive opener

The iDrive opener is recommended only for use on the Wayne Dalton garage door per the manufacturer.

Here is one that can be used on any door.

Here is a link that might be useful: Jackshaft opener

Don't modify a truss without the advice of a structural engineer.

I do not have a torsion bar system. That lets out a lot of openers. I guess I am looking more for an opinion on whether the "bottom chord" is actually a chord or was installed as bracing as I believe it was based on the install and the stick framing techniques of the time

how many nails are in the face nailed connection of the bottom chord and the rafters? Are there any splits or are the nails pulled?

The chords definitely have some functionality keeping the bottom of the rafters from spreading but I can't see the location being so critical that lifting those tie members 6 in. to win clearance will have any significant effect.

Also, are you saying the chord members are 15ft 2x4's?

Replacing them with a 2x6, 2x8, or 2x10 at 6 in. higher and adding more nails to the connection would be an improvement over the 2x4 connection.

You might also want to put some blocking on the ends between the new members and the top of the wall so the ends "bear" on the wall and also provide a little shear support at the roof edges next to the rafters.

Have fun with your new opener.

There are 2 nails and yes it is a 15' 2x4. I am thinking by the look of it that I would improve structure with what I am planning. My main concern is if it is acting as a chord and not a brace.

squirelette - You would be foolish to take advice about how to modify a truss from any unknown person on the internet. Even if the blind advice you get is correct based on what you have described, there may be other important factors that we just can't see or that you don't even know are important. Get a local expert to look at it.

If the structural integrity of the garage depends on 2 nails and a 2x4 then you have more issues to worry about then installing a garage door opener.

If you install and fasten a new 2x4 or 2x6 above the existing before you remove the old one, then nothing has changed other than the connection point.

alice has a point that I haven't seen your specific location, but unless there's something really strange out there what your proposing to do is pretty simple.

The statement is true that free Internet forum advice is worth what you pay for it.

Alice - the point of asking is to find out whether others think my observation is valid before I put off my install until after my holiday back to when I work 7 days a week. and spend a bunch of money on getting people out to give me the certified answer. Because lets face it I will spend more to find out than to do the actual repair and install the opener. That was the question at the beginning of the first post - is it worth the cost

It is actually rather unlikely to be a truss anyway.

Getting a truss design approved for field fabrication has always been a show stopper.

When the exact number and nail placement matters, as well as using the correct grade of wood for each element trusses have always been and remain a factory item.

A conventionally framed roof is a truss design of sorts, but is over-designed to allow for the vagaries if field construction.
Trusses can use less material and lower grade material with less margin in the design, but they must be designed and assembled exactly correctly or risk failure.