I have a 1968 xl with a 428 .uder the dash is a re and gold,or yellow wire where does it go code wise/

Look at the intake. The firing order should be cast into it.

1964 - 1979 Pontiac Engine Codes Bold Type is for manual transmissionStarting in '73,2nd HP # is for Dual Exhaust 1964 326 250 HP 92x,96-0 326 280 HP 94x,97-0 389 230 HP 04L,05L,08R,09R 389 235 HP 22B 389 267 HP 389 283 HP 10A 389 303 HP 25K,26K,27P,28P 389 306 23B,29N 389 325 78X,79J 389 330 32B,34N,33-6 389 348 76X,77J 421 320 35B,38S,43N 421 350 44B,47S,49N 1965 326 250 WP,ZN 326 285 WR,YP 389 256 WA,WB,YA,YB 389 290 WC,YC,YD 389 325 YE,YF 389 333 WE 389 335 WT,YS 389 338 WF,YG 389 360 WS,YR 421 338 HP WG,YH 421 356 WH,YJ 421 376 WJ,YK 1966 326 250 WP,WX,YN,XF 326 285 WR,YP,XG 389 256 WA,WB,YA 389 290 WC,YV,YU,YC,YD 389 325 YX,YL,YW,YF,YE 389 333 WE 389 335 WW,WT,YS,XE 389 360 WV,WS,XS,YR 1967 326 250 HP WP,WX,WC,WH 326 250 HP YO,YN,XF,YJ,XI 326 285 HP WR,XR,WK,WD 326 285 HP YP,XG,YM,XO 400 255 HP XL,XM 400 260 HP 400 265 HP WA,WB 400 265 HP YA,YB,YC,YD 400 290 HP XV,XU 400 293 HP XC 400 325 HP WU,WZ,WQ,WI 400 325 HP YE,YF,YT,XE,XN,XW,XX 400 333 HP WD,WE,WY,XT 400 335 HP WT,WW,YS 400 350 HP XZ,XY,XH,XJ 400 360 HP WS,WV,WR,XS,YZ,XP 428 360 HP WG,Y2,YY 428 376 HP WJ,XK,Y3,YH,Yk 1968 350 265 HP WD,WC,YN,YJ 350 320 HP WR,WK,YP,YM 400 265 HP XM,YA 400 290 HP WA,WB,YC 400 330 HP 400 335 HP WQ,WZ,WI,XN 400 340 HP WU,XT 400 350 HP XZ,XH,YS,YZ 400 360 HP WT,WS,XS,XP 400 366 HP WY,XW 428 375 HP WG,YH 428 390 HP WJ,YK 1969 350 265 HP WC,WP,WM,WU 350 265 HP XL,YJ,XR,YN,XB,YE,YU,XS 350 325 HP WK,WN,XC,XD 350 330 HP WR,WV,XT,XU,YP 400 265 HP XM,YZ,XX,YB,YF 400 290 HP WA,WB,WD,WE,YC,YD 400 330 HP WZ,YT 400 335 HP WQ,YW 400 340 HP 400 345 HP WH,XN 400 350 HP WT,WX,YS,XH 400 366 HP WS,YZ 400 370 HP WW,XP 400 375 HP WI,WY,XY,XW 428 360 HP WG,YL,YH,XE,XJ 428 370 HP WF,XF 428 390 HP WJ,WL,YK,XG 1970 350 255 HP W7,WU,X7,YU 400 265 HP 400 290 HP WE,YD 400 330 HP 400 350 HP WX,WT,XH,YS 400 366 WS,YZ 400 370 WW,WH,XP,XN 455 360 HP WA,YC,YH 455 370 HP WG,XF 1971 350 250 HP WR,WU,WN,WP 350 250 HP XR,YU,YN,YP 400 265 HP WS,WX,XX,YX 400 300 HP WK,WT,YS 455 280 HP WG,YG 455 325 HP WJ,YC 455 335 HP WL,WC,YE 1972 350 160 HP WR,YU,YV,YR 400 200 HP YX,YZ,ZR,ZV,ZX 400 250 HP WK,WS,YS,YT,ZS 455 200 HP 455 220 HP YA,YC,Y4 455 300 WD,WM,YB,YE 1973 350 150,175 HP XR,WV,ZB,ZD 350 150,175 HP Y2,Y7,YR,YV,ZR,ZV 350 150,175 HP WA,WC,WD,WF,WL,WN,XZ 400 170,185 HP W5,XH,XI,X3,X4 400 170,185 HP YI,YP,YX,YZ,Y4,ZK,ZX 400 200,230 HP WK,WS,WP,YN,YX,YT 400 200,230 HP Y3,ZN,ZS,XK,XN,XX 400 200,230 HP XZ,X5,YF,YG,Y6 455 215,250 HP WT,WW,ZZ,ZE,YA,YC 455 215,250 HP YD,YK,ZA,AC,XA,XE,XJ 455 215,250 HP XL,XY,XT,X7,XO,YE 455 290 ZJ,XD 455 310 Z8,X8 1974 350 155,170 HP WA,WB,AA,YA,ZA 350 155,170 HP YB,YC,ZB,YN,YP,YS 350 170,200 HP WN,WP,ZP,YN,YP,YS 400 175,190 HP AH,YH,YJ,ZH,ZJ 400 175,190 HP AD,YF,YK,ZD,ZK 400 200,225 HP WT,WR,Y3,AT,YT 400 200,225 HP YZ,ZT,AD,YL,YM,ZS 455 215,250 HP AU,YR,YU,YW,YX 455 215,250 HP YY,ZU,ZW,ZX,A4 455 215,250 HP 455 290 HP W8,Y8 1975 350 155 HP YB,YA 350 175 HP WN,YN,ZP 400 170 HP 400 185 HP WT,YS,YT,ZT,YM 455 200 HP WX,YU,YW,ZU,ZW 1976 350 160 HP (Early) YB,YA,YP,YR,ZX 350 160 HP (Late) XM,XP,XU,XR,XW,XX,X3,ZF,ZH 350 165 HP 400 170 HP (Early) YJ,YC 400 170 HP (Late) X9,X4,XT,XY,XS,XZ,X8 400 185 HP (Early) WT,Y6,Y7,YS,YT,YY,YZ,ZA,ZK 400 185 HP (Late) WY,X7,ZJ,ZL,X6 455 200 HP WX,Y3,Y4,Z3,Z4,Y8,ZB 1977 301 135 HP WB,YW,YX,YH,YK 350 170 HP YA,YB,XB,XC,Y9 400 180 HP 400 180 HP YU,Y4,XA,Y7,XK 400 200 HP WA,Y6 1978 301 140 HP XA,XC,XL,YM 301 140 HP XD,XB,YL,YP 301 150 HP XF,XH,XU,XW 400 180 HP XJ,XK,X9,YK,YH,YS 400 180 HP YT,YJ,YR,YW,YA,YU 400 220 HP WC,X7 1979 301 135 HP PX7,PX9,PXF 301 135 HP PXH,PXP,PXR 301 150 HP PWA,PWB 301 150 HP PX4,PX6,PXL,PXN 301 150 HP PXS,PXT,PXU,PXW 400 220 HP PWH,LAST 400

This should help, skip to the part where he starts soldering the parts
http://www.youtube.com/watch?v=OhnXUQRQ4u4

You are talking about the wireing harness for the factory (Radio) It is for the indicator lights on the radio,

http://www.painlessperformance.com/webcatalog/p.php?s=1968+chevelle+wiring+diagram&sb=+

go to this site, then click on manual. has all sorts of diagrams for this car.

The wire color code is as follows:

BLK= Black

BRN= Brown

RED= Red

ORG= Orange

YEL= Yellow

GRN= Green

BLU= Blue

GRY= Grey

WHT= White

PPL= Purple

PNK= Pink

TAN= Tan

LT BLU= Light Blue

DK BLU= Dark Blue

LT GRN= Light Green

DK GRN= Dark Green

Let me know if you require any further assistance.

The timing specifications for that vehicle with all V-8 engines 302, 390, 428, 429 are the same.

Spark Plug Type: BF32

Spark Plug Gap: .034 In. - .035 In.

Ignition Point Dwell Angle: 27 Degrees

Ignition Point Gap: .021 In.

Ignition Timing: 6 Degrees Before Top Dead Center

Engine Compression: 150 Psi.

Engine Idle Speed:

302-390-428 Engines: 625 Rpm M/T or 550 Rpm A/T

390 GT Engine: 700 Rpm M/T or 550 Rpm A/T

429 Engine: 550 Rpm M/T or A/T

BLACK - GROUND (-12v)
YELLOW - IGN (+12v WHEN CAR IS ON)
ORANGE - MEMORY (+ 12v ALWAYS ON)
GRAY - BACKLIGHT (ON WITH DASH LIGHTS)
BROWN - DIMMER
PINK - POWER ANTENNA (MAY NOT BE THERE)
LIGHT GREEN/DARK GREEN - RIGHT FRONT SPEAKER +/-
TAN/GRAY - LEFT FRONT SPEAKER +/-
DARK BLUE/LIGHT BLUE - RIGHT REAR SPEAKER +/-
BROWN/YELLOW - LEFT REAR SPEAKER +/-

Use a voltmeter or test light to tell the difference between the gray dash light wire and gray speaker wire, and yellow power wire and yellow speaker wire.

dialtone should go on the green and red wires of the jack for 1 line service, yellow and black for a second line.
Depending on the type of wiring that your dealing with the color code can change. if your wiring has white wires with little dashes of color on them then the code is:
green = white/blue (mostly white with blue dashes)
red = blue/white (mostly blue with white dashes)
black= white/orange (mostly white with orange dashes)
yellow= orange/white (mostly orange with white dashes)

Uder the driver side of the dash is the fuse panel. Remove the cover (if equipped) by pushing in at both ends and pulling off the cover