The firing order is stamped into the block, usually on the front side.
165432
165342
Firing order is: 1,6,5,4,3,2. Got this from my 19997 LeSabre Owners's Manual.
The firing order for a 1985 Buick LeSabre 5.0L is 1-8-4-3-6-5-7-2. This same firing order is used throughout the 1982-1985 Buick LeSabre's with a 5.0L engine.
165432
1-6-5-4-3-2
1-6-5-4-3-2
1-6-5-4-3-2
I believe it's 1-6-5-4-3-2
1-6-5-4-3-2
I believe it's 1-6-5-4-3-2
assuming you have the 3800 3.8L engine the firing order is 1-6-5-4-3-2