Thanks for your reply but I have not found any shear bolt either top or bottom.
Yes there is a bracket that goes over the computer and it has a lip on it as if it should slide off from the front once the two visible screws are removed. Any other thoughts?

I have a 1991 740 Turbo with 260,000 miles. The heater blower needs to be replaced and I cannot remove the fuel ECU short of using a crowbar. I've taken out the two exposed screws and the unit won't budge. What is the secret to getting it off so I can then get to the bracket. Thanks for your help.