PDP 8/E OS8 Boot Floppy and Diagnostics images?

A while back, I wrote a posting regarding RX01 OS/8 boot images for my PDP 8/e. A lot of folks responded off-list with very helpful information. As it turns out, with the gracious help from everyone, I was able to find some programs (dumprest) that did what I needed. I was able to get a working OS/8 boot floppy image onto an actual floppy, and able to boot up from it just fine. I was also able to make some paper tapes of the various MAINDEC diagnostics and load them up and run them. I want to thank everyone who wrote to me with suggestions. It's quite gratifying to have this old machine running with floppies again. Back in the 195/1976 timeframe, I had a summer job that involved a PDP 8/e with dual floppies (I think they were RX01's), and a PC-04, and I wrote a number of math library programs for it, as well as maintaining the system. It really brings back memories when I use PAL, and assemble programs, with the floppy drives clattering away. My next question relates to the RK8E disk controller. The problem with the controller is that it causes apparent conflict on the Omnibus. When the RK8E boardset is installed in the bus, the front panel functions don't work properly. Pressing LOAD ADD with 0's in the switch register results in all 1's showing in the address (but not in the extended address registers), and pressing EXAM causes the address to advance, but weird flickering of bits in the MD register for perhaps a 50ms or so, and then settling down. It's almost as if two or three memory reads are occurring. I can't run any diagnostics or anything, since the RK8E's presence on the bus causes the machine to malfunction. When the RK8E isn't in the system, everything works fine. So, I'm suspecting a few potential areas to look at one the RK8E: A) Omnibus interface chips may be bad (bus drivers/receivers) B) Data break logic (falsely asserting single-cycle data break when it's not valid) C) Timing/Control circuitry I've downloaded the printset for the RK8E, and also have the 8/e Maintenance Manual (Volume 3) with the theory of operation for the RK8E. With this information, I should be able to track down the problems. My initial idea is to replace all Ombibus driver IC's...those which drive the Memory Address (MA) bus, the Memory Data bus, as well as those which drive the Data Break and Interrupt signals. I know it's a shotgun approach, but without an Omnibus extender, or a practical way to power up the boardset outside of the 8/e, it seems the best way to go. Would it make sense to simply remove the 8881's, and then put the boardset in, and see if the machine behaves itself (since the bus is actively pulled up by the Ombibus Load board) to get an idea of the drivers might be bad (or logic that enables them is bad)? The problem is with parts. The RK8E uses SP380's and 8253s' for bus receivers, and 8881's for bus drivers. The 8881 are quad 2-input NAND buffer/drivers, with open collector outputs. I've got a good number of vintage TTL 7401 ICs which match pinout, and are open collector devices, but I'm not sure if the 7401 will work as a replacement for the 8881, since I can't find data on the 8881 I don't know if they are electrically compatible. I do have a few spare 8881s, but not enough to replace all of the 8881's on the RK8E. I don't have any replacements for the SP380s nor the 8253's, which seem to be rather unique, which could be a problem. Anyone out there know if there are 7400-series TTL replacements for these parts? Thanks again, Rick Bensene