a handful of major electronic part suppliers:

• Digikey - good in-stock availability, great catalog, good website.
• Arrow - GREAT in-stock availability, and they now carry AT29C256 Flash PROMs, $5 ea, no minimum. (12/03)
• All American Semiconductor - Good place for AT29 C256 but $50 minimum order.
• Newark - fast, professional shipping
• NuHorizons - I ordered the groupbuy of 500 SI-5151SG 515 X High Side Switches from them.
• MOATES.NET - from DIY-EFI.ORG? Craig offers lots of help and great support. $6 29c256, $7 lowpro ZIF, $6 shipping.
• ProgShop - Germany location, so shipping is expensive to U.S., but it's another resource...

Also, I've had a lot of luck with USBid for sourcing odd and hard to find (discontinued?) parts.

-LegoZ added the following on 10/23/03

Please review this information, if anything is incorrect please remove or correct this as you wish. Just trying to help out. Thanks!

I was able to track down everything I needed from one place. http://www.alliedelec.com They however DO NOT have 29C256. Here are the Allied Stock #'s & Manufacturer Part numbers for chipping ECU's:

This information is listed as follows Allied Stk. #, Manufaturer Part #, and then Description

236-0544 74HC373N Logic,Octal 3 State Latch,Pkg Style 20 Lead PDIP

768-1304 AM27C256-120DC UV EPROM,256K Bit(32K x 8)CMOS EPROM,120ns,Pkg Style 28 Lead CERDIP

900-0012 110-93-320-41-001000 DIP SOCKET,STD SOLDER TAIL,LOW PROFILE(OPEN FRAME),P-TIN/C-GOLD

900-0020 110-93-628-41-001 DIP SOCKET,STD SOLDER TAIL,LOW PROFILE (OPEN FRAME),P-TIN/C-GOLD

926-3401 HY110 Capacitor,Ceramic Disc,Low Voltage,General Purpose,+/-20% tol, .10uF, 12V

-end Lego Z? addition.

See Also Parts For ECUs