It's Indi Belra only. The PSO drop-rates that the Ragol.co.uk database has are quite reliable and complete as far as I know. The Belra Cannon is quite rare, and only available from the pesky Indi Belras from Ultimate Ruins.
Oh well. Not like I'm a Ranger anyway.
Try these drop charts:
Normal
Hard
Very Hard
Ultimate
Alternatively, there are drop charts here, if you need Episode IV, and/or are looking for other useful data:
Edited by Pink: The drop charts are okay since it's IGN, but no posting links to other PSO sites. It's against the forum rules.
Edited by ALMSIVI: Heh, so no useful information then. Ok. o_O
Thanks for the dropcharts! They help a lot. . .

. . . It says I have a 1/700 chance of finding the arm. . . I have a lot to kill.

Little Killer Wrote:. . . It says I have a 1/700 chance of finding the arm. . . I have a lot to kill.
Yes, and no, really. I mean, taking into account the amount of time you spend in Ultimate, getting to 200, if you're patient, odds are you'll find one just casually playing. But then again, I'm sure you'd like it ASAP.
The arm must be wonderful to have, since it's so rare.