Since I just bought all this for the wife's Spiderbox! She's broke 2 of the 3/8" heims just in the last month so I'm replacing them with 1/2", I'm having 4 new A-arms tubes made that are 2" longer and using rubber encased steel bushings instead of the tube & bushings that attaches to the bulkhead to see if it works better.
This is the cheapest route I could find for quality(12,224lb) 1/2" Heims:
2 of these :
http://www.ebay.com/itm/1-2-x-1-2-20...item5ae109bc9e
4 of these :
http://www.ebay.com/itm/1-2-3-8-REDU...item5ae1846ad7
4 of these :
http://www.ebay.com/itm/3-8-CONE-SPA...item5643da5323
1 of these :
http://www.ebay.com/itm/2-DOM-1-OD-x...item5637b2a738 ( you only need 12", you might find a drop @ a steel fab/supplier shop locally cheaper)
This comes to about $65.00 (possible shipping on tubing). You'll want to use 3/8" grade #8 bolts-(I think they're 2-1/2"long) because a 1/2" hole in the spindle flange doesn't leave very much material around the cone spacer. A 1" bi-metal hole saw is what you should use if you have a drill press and you want to make a jig to hold the A-arm since the bit cuts it in two leaving your saddle cut. Simplest route is to cut the A-arm in two down the center of the bent and just weld in the short piece of tubing at the correct angle to be horizontal with the ground, then weld the bung in the tubing(You only weld the lip end of the bung). You can try to weld the bung without the tubing but if you overheat the weld, you'll be chasing the threads. If you're worried about your welding then cut a gusset at the backend of the tubing and weld it around the radius of the A-arm.