They might have to if GE doesn't get it's butt in gear.;)

The part about pre-stressing the structure during assembly: I'm not certain that they do the wing-body joins with the weights attached. The weights are attached after the landing gear is put on and the plane is set on the factory floor. The wing-body join jig might have some tooling to apply pre loads while tightening the bolts. But moving sections around and working in the jig would be too clumsy with a bunch of blocks to bump into.

The idea that the concrete blocks are necessary to properly stress the wing structure is a popular myth (even heard from time to time within Boeing). But it is just that - a myth. The engines are normally the last thing installed before the aircraft rolls out the door. The flight loads the wing is designed for are far, far greater than the static weight of an engine hanging off the strut (and yes Ken, we've always called them struts - in fact the now Propulsion Systems Division was once known as "Power Pack and Strut".
As noted, I occasionally saw the nose gear chained to concrete blocks or to the ground when the concrete block engines were not readily available.
Once, many years ago, we were taxing to the far south end of Paine Field preparing for takeoff for a flight test. I saw a brand new 747-400 parked in a remote corner of the field that looked really strange, but in a good way. It took me a second to figure out why - the wing was complete clean. No engines, no struts, not even any pylons :p. I have to admit that hanging all that engine hardware on the wing destroys the clean lines of the wing. There were also chains tying the nose gear to a large block of concrete. Come to find out, Rolls had gotten behind producing RB211-524 engines for the 747-400. One operator decided they didn't need their new 747 right away so the pushed the engineless aircraft to a far corner of the field for six months while Rolls production was able to catch back up.

Boeing didn't have a bust. They just had reckless cost cutting.

"Reckless cost cutting?" And this assertion is based on what?

Let's see, 737 production is delayed due to shortages of fuselages (provided by an independent vendor), and engines (also provided by an independent vendor).
Very interesting logic that concludes the delays are caused by reckless cost cutting at Boeing :rolleyes:

Now, one might question the wisdom of Boeing selling off the Wichita based 737 fuselage production facilities to Spirit - heck I'd even agree that was probably a bad move. But that move was made over a decade ago, by people no longer involved in Boeing.

RickNRoll
 

RickN, You see it inverted
We are in a boom.
It will all be clear when You level out
Blueside
Remember
Up;)

Boeing doesn't handle unforeseen events well. It's likely that some of the workforce has been diverted from scheduled work to out of sequence tasks on the unfinished planes as parts trickle in. It's also possible that they have run out of parking spaces for engineless planes on the flight line and are holding up these fuselages.

When I worked there, I was involved with a system that delivered engineering functional tests to the shop floor. We built it so any test was available any time. Just in case a job slid in the schedule. The replacement for that system provided little of that functionality. "Plan for success" was the mantra and anything that didn't conform to the normal schedule was insanely difficult to access (managers' logins, special approvals, etc.). I fear that delays due to external causes will result in the Renton shop floor beginning to resemble a Chinese fire drill (apologies for the possible racist connotations of that remark).