The Medallions - Buick 59 - help with rhythm?

Could be. Or 2 bars 4/4, 2 bars 5/4.

I'm just guessing. I can't really feel the '1' after the 2nd bar at all. 

They seem to be doing it as a straight 12 bar shuffle here; http://www.youtube.com/watch?v=K0RXGDcXa0E

Wrt to the bass line, I am counting it more as 4 measures of 4/4 and a measure of 2/4 instead of counting that last measure as 6/4 … reason being, it just sounds like they stuck 2 extra notes in there to get the vocals to come around.  It’s not like a measure of 6/4 where they are completing a musical idea.

The vocals are arranged so they don’t step on each other.  The “call” picks up on beat 4 at the end of the intro and stops on beat 1 of measure 3.  The “response” (Buick 59, Buick 59) starts on beat 3 of measure 3 and stops on beat 1 of what would be measure 5.  From that point on, to keep the math correct and prevent the vocals from stepping on each other, that 5^th measure is a measure of 2/4 with the response stopping on beat 1 and the call picking up on beat 2.

It’s not random … an arranger sat down and did the math.

… just a drummers perspective.

I think it's definitely planned. I understand when blues/folk performers add random beats here and there to fit the words, but that's more of a spontaneous thing which can change from performance to performance, and is usually when it's a solo performance. I do it myself when improvising solo fingerpicking pieces. However when you have a band cutting a track in the studio I'm pretty sure the structure was deliberate, even if the performances were flexible to some extent. 

I hear it a lot in traditional Irish tunes, especially when there's a vocal. However, when a band takes a traditional song and turns it into an arrangement for multiple musicians, they still sometimes throw those "random" extra beats in, only they're not so random. It's a way of giving an ensemble performance a more authentic, organic feeling. Take P Stands For Paddy as recorded by Planxty, plenty of extra beats thrown in, but it's obvious they've practiced the bejesus out of that arrangement. 

But it still throws me, and I have a hard time counting it, especially in a tune like this where the bass line is so familiar yet throws you that curve ball. I often wonder whether it sounds odd to me simply because I have a musical mind which looks out for this stuff, whereas if you never think about music theory, it mind sound totally natural. Another example is Blackwaterside by Bert Jansch, I transcribed it years ago and it took me ages to get my head around all the bars of different length. But I remember playing it for a non-musical friend and asked him whether he found anything weird about the rhythm...he said he didn't. 

sharke

jamesg1213


They seem to be doing it as a straight 12 bar shuffle here; http://www.youtube.com/watch?v=K0RXGDcXa0E

Maybe they focus-grouped it 

That's funny ... I just listened to this one and you are probably right.  The extra two beats were probably deemed too cerebral for the modern listener.
 
In this version they just shifted the response to beat 1 instead of beat 3 ... and just let the call and response step on each other.  Again, I suspect somebody gave the vocal arrangement a lot of thought in the original version.

Interesting song pick, Sharke. Definitely get ones attention.
 
My $.02, I go with Yorolpal in this. Performance is simple. Lead vocal track, backup vocals, hand-claps, piano player (playing bass and chords). I think the lead vocalist just went with it, and might have a poor sense of song structure/timing(?). The piano player just followed behind (or played catchup) in some spots. The handclaps are not an issue because they just follow the steady beat. The backup singers aren't an issue. They also come in based on the lead vocal line. Everything is keyed off the lead vocalist. I wouldn't doubt if this was a one-shot recording. It worked well enough, so they kept it.
 
And as the link Jamesg1213 posted, this shows a more recent performance and it is straightforward with the timing.
 
I do like the song (odd timing and all).