Yes, the D63 is the non-storage version of the DM63. Nice machines - my "default" scope. I've written a few things about it on this forum and here:
http://www.markhennessy.co.uk/dm63/
Indeed there are 2 Tek chips in there. I've never heard of the sweep generator failing, but I've had the other IC fail in mine. It did fail previously before I acquired the unit, so I suspect another fault was lurking on the timebase module. I've had a lot of conversations about these over the years, but no conclusive reports of other failures.
The usual problems are capacitors (surprise, surprise!) and high-value resistors failing in the EHT module. Yes, the Y-out transistors can be problematic, but substitutes are available. Other random failures are what you'd expect for gear of that age. All faults I've had are written up on my pages...
I'd say the build quality is several notches about the usual Telequipment stuff. Similar to the D83 outwardly, but better again IMHO (I have a couple of D83s as well). I think the chassis is derived from the Tek 5000 series, but could be wrong (I'm going by these pictures:
http://www.wellenkino.de/ - never seen one in the flesh)
Officially, they were sold as 15MHz 'scopes. The manual says -3dB at 18MHz. In practice, it's more like 20MHz when lined up (the test fixture is handy for that, but very rare). Plenty for audio. Triggering is fairly basic, but good enough.
The V4 plugins are the most common, but look out for the V3 differential. This goes down to 50uV/div, and is very useful for low-frequency work. I only have one - I find it so very useful that I'm uncomfortable about not having a spare. It has a Y-out BNC which I plug into a powered speaker - can't tell you how useful that is for audio and radio stuff
I wonder if the storage version might be of more use for an SA - the variable persistence mode is especially useful.
Edge connectors are 0.15" fingers on the plug-in PCB, and standard sockets on the main board.
Just a thought: a while back I bought the remains of a V4 plugin from a forum member. Most of it is there, but it will be quite a project to put it all back together again. So, ideal for your project - saves wrecking a good one. If that's of interest, let me know - it's yours for what I paid for it.
Good luck!
Mark