It's a bitch right now.

Alternators are shipped in "case assortments". The current July/August assortment contains:

1 Swerve (red vette) *new
2 Grimlock (silver stang) - first seen December 04
1 Swindle (yellow jeep) - first seen December 04

The upcoming assortment contains

1 Prowl (patroll RSX-S) *new
1 Decepticharge (yellow S2000) *new
1 Wheeljack (white stang) - first seen May 04
1 Swindle (yellow jeep) - first seen December 04

The distrubution of these toys seems very random. You figure since Swerve is brand new, we'd see him for a while ... nope. 1 case and he's done.

Shockblast was seen in March for 1 case, and May for 1 case. He's not scheduled anytime soon.