Without looking I can't say for sure, but I believe there are enough differences that it wont work.

Here is what I am thinking:
1) call zzp and see if they will flash a computer without the rear o2
2) get a downpipe from zzp with a new cat in it
3) If the lean code comes back then change fuel pump and maybe upgrade the wiring to a larger size

I may be wrong, but I don't think your P0171 is coming from the rear(down stream)sensor. The rear sensor only monitors if your cat is working. It should be coming from the front(upstream)sensor. This is the one that when you are looking down between the engine and fire wall.

Yes you are right I am also getting a p0420 code
Lucky me
any ideas?

ok called zzp and he can not reflash a 1996 computer,

Can I take the inside computer and engine computer (engine harness ??) from lets say from a 1999 olds lss and put in my 1996 olds lss Has anybody done this? or can it be done?
Also my tranny is the one with the vacuum going to it

thanks

I swapped both computers from a 1997 bonneville and the scanner still stay obd2 calf
but the scanner now show NA for the second o2 sensor It still show power to the o2. Car has a better idle 810 rpm instead of 745 rpm and rough. Also what would it take to swap in a tranny that did not have a vacuum modulor Because if I swapped out the tranny I could go for the 98 + stlye computer
Any idea??

The rear sensor is only there for the cat, nothing more. The front sensor is what'* causing the lean code. We just had a member with same code and found low startup fuel pressure cased it. Reset code, turn key to run, wait a moment to build up pressure, then start. See if that helps.

code will come back on after clearing the codes sometimes 2 minutes sometimes 2 hours

update?

I found that the exhaust pipe is hitting the sway bar so what I am thinking that it is opening at the donut gasket and sucking air in and there by causing the code
I have to come up with the funds to fix it and see if that works.
I will post when I get it done