The heat shrink I ordered was too large (edited for 77mm in above post). That's what I get for not measuring. 
About the best fit will be 77 mm heat shrink.
These packs are SLIGHTLY heavier than the stock ones < 20 gram difference using a cheap postal scale.
Otherwise, these batteries are the same size as the stock ones.
I used some clear shrink I had lying around from my RC hobby days that I ended up trying on one pack, I'll build the other pack and re-shrink the first one once I get the right sized stuff.
If by chance you end up ordering this stuff, or similar, here are a few tips:
* Use battery connecting strip (tin, etc) in the same configuration as the stock pack. The only difference I might recommend is to route the negative strip to the black wire through the middle of the 4 cells arranged in a square (might cut through the heat shrink if on the outside like the stock pack). You'll need to solder the black wire to the strip before you solder the strip to the battery and use caution not to heat the strip and cause the solder on that end of the strip to re-melt when solderiong the strip to the battery.
* If you don't use a connecting strip on the negative terminal of the pack, you'll lose some length on your battery wire.
* Don't cut the stock wiring! I cut the shrink off and de-soldered the old strip from the wire and touched the wire up with fresh solder.
* You can forego the one strip for the positive wire and just solder the wire right to the cell.
* Keep solder amount to a minimum, and try to keep the strips as flat as you can. It helps to straighten them out before you try to solder them down. At the same time, you want a good solid connection with good "flow" of solder between the strip and the battery.
* Make sure to lightly sand the ends of the cells to remove any oxide and provide a clean surface. Tin the ends of the cells with a minimal amount of solder, just enough to "wet" it in an area a bit bigger in diameter than the strip's width.
* Use an iron / gun with sufficient heat. I used my trusty ole' Weller 135 watt. However, try your best not to heat up the cells with the iron or gun, this may take some life off of them. You might want to stop and let the cell cool down if you're having trouble.
* Before you solder anything, glue the cells together in the same arrangement as the stock pack (positive / negative ends). I used thin CA with Zip Kicker from a q-tip to speed up the cure time. Just a drop on either side where the cells touch will wick down the entire length. It helps to use a square corner to line up the cells.
If you've built sub-c RC packs, the process is really no different:
1. Line up and square up the cells and glue them together.
2. Sand the ends of the cells, tin them with solder.
3. Solder battery bars / connecting strips between the cells.
4. Solder the wires to the ends (to strip or battery terminal).
I don't enjoy making up packs - the biggest pain for me is soldering the cells, and I've done more soldering in my life than most (I soldered boards at my first job, thousands of them, nearly 20 years ago). It's difficult to get a good looking result - but, with patience, you can get a result that will work well (good flow, no "cold solder"). That said, these cells are easier to work than sub-c packs.
I did a slow charge on these, 200 mA overnight. I used an Imax B6, I pulled the terminals out of the connector and used alligator clips on the terminals. The cells took a bit over 1800 mAh (over 9 hours). I haven't done a discharge on them to see how many mAh they'll deliver, but I bet it's pretty close to the rated 1500 mAh.
The Robonova battery charger should work fine with these cells (haven't tried it yet), it'll just take a little longer, but you'll get more run time as a result. As with all NiCd / NiMh cells, it's said that the cells will take a few cycles to come up to their potential.
These should make a great replacement for the stock pack, and a few more mAh doesn't hurt. 
Take Care,
Paul
PS - A word of caution - if you haven't soldered before, this isn't going to be fun, and I don't recommend this as a first soldering project...Statistics: Posted by PaulL — Sat Jul 13, 2013 7:43 am
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